JP2003344869A - Liquid crystal panel and manufacturing method therefor, and projection type liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent temperature rise by minimizing light absorption of a liquid crystal panel. <P>SOLUTION: In a pixel electrode 18 and a transparent electrode 22 on the counter electrode side, the thickness of a light incident path is set thin to 10-50 nm, and the thickness of the parts other than the light incident path part is set to 80-500 nm. The transparent electrode film is made thick in the connection part of a drain electrode 16 and a pixel electrode 18, and also in the connection part of the transparent electrode 22 on the counter substrate side and an active matrix substrate 1. Incident light focusing lenses are arranged on the counter substrate 2 correspondingly to each pixel. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal panel, a manufacturing method thereof, and a projection type liquid crystal display device using the liquid crystal panel.

[0002]

2. Description of the Related Art In a liquid crystal panel, a pair of substrates are opposed to each other with a liquid crystal layer as a display medium interposed therebetween, and pixel electrodes (active matrix substrate side) provided in a matrix on one substrate (active matrix substrate). A voltage is applied between the electrode) and the counter substrate side electrode provided on the other substrate (counter substrate) to change the alignment state of the liquid crystal molecules in the liquid crystal layer for each pixel, and to enter the liquid crystal layer. The display panel displays an image by controlling the transmission / scattering state of incident light for each pixel.

In a direct-viewing type liquid crystal display device in which an image displayed on a liquid crystal panel is directly viewed, the intensity of light applied to the liquid crystal panel is not great, but the liquid crystal panel is irradiated with light from a light source to produce a screen. In a projection-type liquid crystal display device that projects and displays an image on top, the intensity of light applied to the liquid crystal panel is several million lx or more. Further, in the future, in order to improve the illuminance on the screen, in the projection type liquid crystal display device, the intensity of light applied to the liquid crystal panel tends to further increase.

Generally, a transparent conductive film is used as a pixel electrode and an electrode on the counter substrate side which constitute each pixel, but the light transmittance thereof is not 100% as a matter of course, and a part of incident light is used. Is converted to heat. Therefore, even if the air cooling is forcibly performed, the temperature of the liquid crystal panel will be 60 to 60 ° C.
℃ rises. It is known that the optical characteristics of liquid crystal materials change depending on the temperature. When the temperature of the liquid crystal panel rises in this way, the optical characteristics of the liquid crystal materials may change, and a good display state may not be obtained. is there.

In order to prevent such a temperature rise of the liquid crystal panel, for example, in Japanese Patent Publication No. 6-58474, a cooler filled with a cooling liquid is brought into close contact with the liquid crystal panel, and the liquid crystal panel is cooled by liquid heat transfer cooling. A liquid crystal display device for cooling is disclosed. Further, JP-A-9-113906 discloses a liquid crystal display device in which a heat-dissipating glass substrate is attached to a liquid crystal panel and the liquid crystal panel is cooled by solid-state heat transfer cooling.

[0006]

The temperature of the liquid crystal panel is
It is determined by the balance between heat absorption and heat dissipation. The conventional technology currently used to prevent the temperature rise of the liquid crystal panel is
It focuses on heat dissipation. However, since the liquid crystal panel uses a glass substrate having a lower thermal conductivity than conductors and semiconductors, a great effect cannot be expected if only heat dissipation is used to prevent the temperature rise of the liquid crystal panel. .

The present invention has been made in view of such circumstances, and a liquid crystal panel capable of preventing temperature rise by minimizing light absorption of the liquid crystal panel, a manufacturing method thereof, and a projection type liquid crystal display. The purpose is to provide a device.

[0008]

The liquid crystal panel of the present invention comprises:
In a liquid crystal panel in which a pair of substrates each provided with a transparent electrode are opposed to each other with a liquid crystal layer in between, the thickness of the transparent electrode provided on at least one substrate is 10 nm or more.
It is set to 0 nm or less, and thereby the above object is achieved.

The liquid crystal panel of the present invention is a liquid crystal panel in which a pair of substrates each provided with a transparent electrode are opposed to each other with a liquid crystal layer in between, and the transparent electrode provided on at least one of the substrates has a light incident path portion. Has a smaller thickness than the other portions, thereby achieving the above object.

Preferably, in the transparent electrode, the thickness of the light incident path portion is 10 nm or more and 50 nm or less.

Further, preferably, in the transparent electrode, the thickness of the portion other than the light incident path portion is 80 nm or more and 500 nm or less.

The liquid crystal panel of the present invention is a liquid crystal panel in which a pair of substrates each provided with a transparent electrode are opposed to each other with a liquid crystal layer sandwiched therebetween, and the thickness of the transparent electrode provided on at least one substrate is 10 nm or more. The thickness is set to 50 nm or less, and a metal film or an intermetallic compound film is laminated on the transparent electrode in a portion other than the light incident path portion, whereby the above object is achieved.

Preferably, among the pair of substrates, the active matrix substrate has a plurality of scanning wirings and a plurality of signal wirings intersecting with each other, and switching elements arranged in a matrix near each intersection of both wirings. An active matrix substrate side transparent electrode connected to the switching element is provided, and a scanning signal for turning on / off the switching element is supplied from the scanning wiring, and at the same time, from the signal wiring via the switching element. A signal is supplied to the active matrix substrate-side transparent electrode, and the counter substrate is provided with a counter substrate-side transparent electrode, and a matrix-shaped matrix is provided at a portion where the active matrix substrate-side transparent electrode and the counter substrate-side transparent electrode face each other. Pixels are configured.

Further, preferably, in the active matrix substrate, the switching element and the active matrix substrate-side transparent electrode are connected through a contact hole, and in the contact hole portion,
The thickness of the transparent electrode on the active matrix substrate side is 80
It is set to not less than nm and not more than 500 nm.

Further, preferably, in the active matrix substrate, the switching element and the transparent electrode on the active matrix substrate side are connected through a contact hole, and in the contact hole portion,
The thickness of the transparent electrode on the active matrix substrate side is 10
The thickness is not less than 50 nm and not more than 50 nm, and a metal film or an intermetallic compound film is laminated on the active matrix substrate side transparent electrode.

Further, preferably, the counter substrate is electrically connected to the active matrix substrate, and the thickness of the counter substrate side transparent electrode is 80 nm or more and 500 nm or less at the connection portion.

Further, preferably, the counter substrate is electrically connected to the active matrix substrate, and the thickness of the counter substrate side transparent electrode is 10 nm or more and 50 nm or less at the connecting portion, A metal film or an intermetallic compound film is laminated on the side transparent electrode.

More preferably, the counter substrate is provided with an incident light condensing lens corresponding to each pixel.

According to the method of manufacturing a liquid crystal panel of the present invention, a transparent conductive film having a thickness of 80 nm or more and 500 n or more is formed on at least one substrate.
The transparent conductive film in the light incident path portion is etched to have a thickness of 10 nm or more and 50 nm or less.

According to the method of manufacturing a liquid crystal panel of the present invention, a transparent conductive film is provided on at least one substrate in a range of 10 nm to 50 nm.
After being formed to have the following thickness and laminating a metal film or an intermetallic compound film on the transparent conductive film, the metal film or the intermetallic compound film in the light incident path portion is removed by etching.

The projection type liquid crystal display device of the present invention irradiates the liquid crystal panel of the present invention with light from a light source to project an image on a screen for display, thereby achieving the above object. .

The operation of the present invention will be described below.

In the active matrix type liquid crystal panel, ITO (Indium Ti) is the main material used as transparent electrodes (pixel electrodes and counter substrate side electrodes).
nOxide), and the film thickness is 100 nm to 200
nm. This thickness is set according to the case where a bus line and a pixel electrode are used in a simple matrix type liquid crystal panel or the like. However, as a result of detailed examination of the characteristics required for the transparent electrode by the inventor of the present application, it was found that the film thickness can be significantly reduced.

The light applied to the liquid crystal panel is mainly
It is absorbed by the transparent electrode, the alignment film, the liquid crystal layer and the bus line (wiring). Of these, it is easiest to review the transparent electrode that does not directly affect the operation of the switching element TFT or the liquid crystal operation. In addition, the transparent electrode,
The light transmittance is not so high as the name suggests. The light transmittance of a generally used ITO film is around 90%, and from the viewpoint of the brightness of the liquid crystal layer, this transmittance is 95%.
Even so, only 5% is improved. However,
From the viewpoint of light absorption by the ITO film, the difference is double at 10% and 5%. In view of the above points, in the present invention, the structure (particularly the thickness) of the transparent electrode of the liquid crystal panel was reviewed.

In the present invention, the thickness of the transparent electrode is made thinner than the conventional one, for example, by setting it to 10 nm or more and 50 nm or less, the light absorptivity of the transparent electrode is lowered to reduce the temperature of the liquid crystal panel. The rise can be significantly reduced.

In particular, in the projection type liquid crystal display device, the intensity of light applied to the liquid crystal panel is higher than that in the direct view type liquid crystal display device, and therefore, it is important to reduce the light absorption rate by the transparent electrode. It is very effective in preventing the temperature rise. Further, in the projection type liquid crystal display device, a lens for condensing incident light is often provided at the opening of each pixel on the counter substrate side. In this case, a source bus line, a light shielding film, or the like is provided. The absorption of light due to is reduced, and the temperature rise of the liquid crystal panel can be prevented.

The thickness of the transparent electrode other than the light incident path portion may be set thicker than that of the light incident path portion, for example, 8
It can be 0 nm or more and 500 nm or less.

In addition, a transparent electrode film is formed at the connection portion (contact hole portion) between the drain electrode of the TFT, which is a switching element, and the transparent pixel electrode, and at the connection portion (common transition portion) between the counter substrate and the active matrix substrate. If it is thin, it may cause poor connection. Therefore, it is preferable to increase the film thickness of the transparent electrode or stack a metal film or an intermetallic compound film on the transparent electrode to improve the connection state.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

FIG. 1 is a sectional view showing the structure of the main part of an active matrix type liquid crystal panel, and FIG.
It is a top view which shows the structure for 1 pixel of the active matrix substrate.

In this liquid crystal panel 100, an active matrix substrate 1 and a counter substrate 2 are arranged so as to face each other with a liquid crystal layer 3 in between.

The active matrix substrate 1 is provided with a plurality of gate bus lines (scanning lines) 14 and a plurality of source bus lines (signal lines) 15 which intersect each other on a transparent substrate 11 made of glass or the like. Pixel transistors 20 as switching elements are provided near the intersections of the gate bus lines 14 and the source bus lines 15, respectively, and the pixel transistors 20 are arranged in a matrix.

The pixel transistor 20 includes a gate bus line 1 on the Si layer 12 with a gate insulating film 13 interposed therebetween.
4 is provided with a gate electrode, and an interlayer insulating film 17 is provided thereon. The Si layer 12 is
It is connected to a source electrode forming a part of the source bus line 15 through a contact hole 15a provided in the gate insulating film 13 and the interlayer insulating film 17, and connected to a drain electrode 16 through a contact hole 16a. There is.

A pixel electrode 18 made of a transparent conductive film is provided on the interlayer insulating film 17 so as to partially overlap the gate bus line 14 and the source bus line 15.
The pixel electrode 18 is the drain electrode 16 of the TFT 20 via the contact hole 18 a provided in the interlayer insulating film 17.
Connected with. Further, the pixel electrode 18 also partially overlaps with the adjacent gate bus line (Cs bus line) 14a, and the pixel electrode 18, the interlayer insulating film 17, and the Cs electrode overlapping part of the Cs bus line 14a overlap each other. Then, a capacity (Cs capacity) is configured. On the pixel electrode 18,
An alignment film 19 for aligning the liquid crystal molecules in the liquid crystal layer is provided.

In the counter substrate 2, a counter transparent electrode 22 made of a transparent conductive film and an alignment film 23 are provided in this order on the transparent substrate 21 made of glass or the like from the substrate side, and the pixel electrode 18 and the counter transparent electrode are provided. The portion of the liquid crystal layer 3 that faces 22 is a matrix-shaped pixel portion.

Note that, in FIGS. 1 and 2, a light shielding film or the like for shielding the light radiated to the pixel transistor portion and the Cs portion is omitted.

Next, in the liquid crystal panel thus constructed, the resistance value required for the transparent electrode will be considered.

FIG. 3 (a) shows the liquid crystal panel 100 of FIG.
It is an equivalent circuit diagram which shows the circuit structure for a pixel.

The gate electrode of the pixel transistor 20 is connected to the gate bus line 14, and the pixel transistor 2
The source electrode of 0 is connected to the source bus line 15. The drain electrode of the pixel transistor 20 is connected to the liquid crystal capacitor 31 provided in the opposing portion of the pixel electrode 18 and the opposing transparent electrode 22, and in parallel with the liquid crystal capacitor 31,
A Cs capacitor 32 is provided. In the Cs capacitor 32, one electrode is the pixel electrode 18, and the other electrode, the Cs electrode, is connected to the Cs bus line 14a (adjacent gate bus line 14).

Next, the operation of the liquid crystal panel thus constructed will be described.

Generally, in a driver monolithic liquid crystal display device in which a liquid crystal panel, a gate driver and a source driver are provided on the same substrate, the operation of the liquid crystal panel is performed as follows.

First, when a scanning signal for turning on the pixel transistor 20 is supplied from the gate driver to the selected gate bus line 14, the pixel transistor 20 connected to the selected gate bus line 14 is supplied. Are all turned on. Then, when a necessary potential (data signal) is supplied from the source driver to the selected source bus line 15, the potential is applied via the pixel transistor 20 to the liquid crystal capacitor 31 and the Cs capacitor 32.
Given to. In reality, a large amount of electric charge is supplied from the source bus line 15 having a large capacitance to the pixel transistor 20.
The liquid crystal capacitor 31 and the Cs capacitor 32 are charged through the capacitor and have a predetermined potential.

However, FIG. 3B and FIG.
As shown in (c), the ON resistance (Ron) of the pixel transistor 20 and the resistance due to the pixel electrode 18 exist between the source bus line 15 and the liquid crystal capacitance 31. Further, the counter side transparent electrode 22 also has a resistance (R counter), and the Cs bus line 14a also has a Cs bus line resistance. 3B is an equivalent circuit diagram showing a circuit configuration along a certain gate bus line, and FIG. 3C is an equivalent circuit diagram obtained by extracting only the counter substrate side in FIG. 3B. is there.

Therefore, when the liquid crystal capacitor 31 and the Cs capacitor are charged by the potential (current i) from the source bus line 15, the liquid crystal capacitor 31 and the Cs capacitor cannot be charged instantaneously, but the next gate bus line is selected for charging. It should be done by.

The charge / discharge of the liquid crystal capacitor 31 and the Cs capacitor 32 is performed by the wiring resistance (Cs shown in FIGS. 3A and 3B).
Bus line resistance, counter substrate side transparent electrode resistance (R counter),
Pixel electrode resistance) and the ON resistance (Ron) of the pixel transistor and the capacitance, the charge / discharge has a certain time constant, and τ = C (liquid crystal capacitance) × (counter substrate side transparent electrode resistance (R counter) × Horizontal number of pixels (n) + pixel electrode resistance + pixel transistor ON resistance (Ron) τ = Cs (Cs capacitance) × (Cs bus line resistance × horizontal pixel number (n) + pixel transistor ON resistance (Ro)
n)). However, in the above formula, the number of pixels in the horizontal direction is used as it is, and in a driver monolithic liquid crystal display device, etc., in general, charging of pixels in the horizontal direction is not started at once, so the time constant τ is overestimated in the above formula. To be

When an ITO film is used as the transparent electrode, its specific resistance is generally 2E-4 Ωcm to 5E-4 Ωcm.
And 20Ω / □ to 50 when the film thickness is 100 nm
It becomes Ω / □. Since the panel shape of the liquid crystal panel and the shape of the pixel electrode are substantially square, the resistance of the transparent electrode (pixel electrode and counter electrode) is 20Ω to 50Ω regardless of the panel size.

The Cs bus line resistance is 1 kΩ to 10 kΩ.
The liquid crystal capacitance 31 is 1 fF to 100 fF, and the Cs capacitance 32 is 10 fF to 1 pF. A small liquid crystal panel such as a liquid crystal panel used for projection has a small capacitance, and the bus line resistance depends on the panel design, but it is several tens of k.
It becomes Ω.

For example, assuming that the transparent electrode resistance is 50Ω, the number of horizontal pixels is 1000 (about XGA screen), the ON resistance of the pixel transistor is 500 kΩ, and the liquid crystal capacitance is 100 fF, the time constant τ to the liquid crystal capacitance 31 affected by the characteristics of the transparent electrode is set. When calculated, it becomes 60 nS. In general, since the horizontal retrace time is several μS, this time constant of 60 nS is overestimated as described above, but it can be seen that there is a sufficient margin. On the other hand, the time constant τ of the Cs capacitor 32 has nothing to do with the transparent electrode.

Therefore, the resistance value of the transparent electrode is, for example, 20Ω to 50Ω (film thickness 10
It can be seen that even if it is 10 times (0 nm), the panel characteristics are not affected at all.

Next, the thickness of the transparent electrode will be considered.

As described above, even if the film thickness of the transparent electrode film is reduced to 10 nm or more and 50 nm or less to increase the resistance value, no problem occurs in the display characteristics of the liquid crystal panel.

On the other hand, in the liquid crystal panel 100, the pixel electrode 18 and the drain electrode 1 of the pixel transistor 20.
6 is connected via a contact hole 18a in the interlayer insulating film 17.

The contact hole 18a has a depth of 0.1 μm.
m-1 μm, and the diameter thereof is 0.5 μm-5 μm. In a liquid crystal panel for projection use, the contact hole is formed by using anisotropic etching, so that the contact hole is formed almost vertically without inclination, and the ratio of the hole diameter to the thickness of the contact hole ( Aspect ratio) becomes higher. In addition, the transparent electrode film has a CV with good step coverage (step coverage).
The film forming technique by the D method is not established, and the film is usually formed by the sputtering method.

As a result, the pixel electrode 18 has the coverage characteristics as shown in FIGS. 4A and 4B, and when the transparent electrode film is thin as shown in FIG. 4A. Contact failure occurs between the drain electrode 16 and the drain electrode 16. Although it is possible to provide a step in the shape of the contact hole as shown in FIG. 4C, the manufacturing process becomes complicated, and the area occupied by the contact hole increases, resulting in a decrease in the pixel aperture ratio. It is not preferable because it invites.

Therefore, the pixel electrode 18 and the drain electrode 16
It is preferable to increase the film thickness of the pixel electrode in the contact hole portion connecting with.

Regarding the counter side transparent electrode 22 provided on the counter substrate 2, the active matrix substrate 1
It is necessary to electrically connect to the external extraction electrode terminal provided on the side (common transition). This connection is made by interposing conductive particles.
In order to reduce the contact resistance between the counter substrate and the active matrix substrate shown in (c), pressure is applied to both substrates until the conductor particles are deformed. Therefore, if the transparent electrode 22 on the opposite side is thin, a perfect continuous film cannot be obtained, so that the mechanical strength becomes insufficient, and scratches, peeling, etc. occur, resulting in contact failure.

Therefore, at the connecting portion between the opposite transparent electrode 22 and the active matrix substrate 1, the opposite transparent electrode 2 is formed.
It is preferable to increase the film thickness of 2.

ITO used as a transparent electrode film
The film is polycrystalline and not uniform across its thickness. Figure 5
As shown in FIG. 5, in the initial stage of growth of the ITO film, island-shaped grain growth starts and gradually grows into a continuous film. Therefore,
The lower limit of the film thickness at which the ITO film can be used as a continuous film is around 10 nm.

Next, the light absorption of the transparent electrode film will be considered.

When the liquid crystal panel is used for direct view, the intensity of light irradiated on the liquid crystal panel is not so large that no particular problem occurs. However, for projection use, the intensity of light irradiated on the liquid crystal panel is large. However, the optical characteristics of the liquid crystal are greatly affected by the conversion of part of it into heat.

A glass substrate, a transparent electrode, an alignment film, a liquid crystal, an interlayer insulating film, etc. are provided in the path of the incident light. Here, except the transparent electrode, the transmittance is high, or
It is difficult to change the thickness due to the limitation due to the liquid crystal operation.

The transparent electrode does not have a high light transmittance as the name suggests, and is generally used for ITO.
The film absorbs about 10% of visible light. As the transparent conductive film, an ITO film, a SnO ₂ film, a ZnO film and the like are known, but in view of workability, specific resistance and transmittance,
The ITO film is often used. The ITO film will be described below, but the same applies to other transparent conductive films.

The light transmittance of the ITO film changes to a high range in the visible light range depending on the film forming conditions and heat treatment conditions. Under the manufacturing conditions currently used, the light transmittance is about 90% at a film thickness of about 100 nm. In order to improve the film quality of the ITO film and increase the light transmittance, it is effective to raise the film formation temperature and the heat treatment temperature. However, the counter substrate has a heat resistance under the ITO film. Since the color filter layer and the lens which are not provided are provided, the film formation temperature and the heat treatment temperature have an upper limit of about 200 ° C. Not all LCD panels have this kind of restriction,
It is difficult to improve the quality of the ITO film.

The transmittance (absorptivity) of light incident on the transparent conductive film is such that, with respect to the film thickness, light transmittance = EXP (-absorption coefficient * film thickness) light absorptivity = 1-light transmittance. Become. The absorption coefficient of the ITO film is about 1E6 (1 / m), and as shown in FIG. 6, its light transmittance and light absorption rate change linearly with the film thickness, for example, the thickness of the transparent electrode. The light absorption can be halved by halving. Therefore, reducing the film thickness of the transparent electrode is the simplest and most effective method for reducing the light absorption rate.

Although the above points are well known individually, in the liquid crystal panel of the present invention, by comprehensively examining these contents and incorporating them into the device structure, the light radiated to the liquid crystal panel can be controlled. It suppresses absorption.

The embodiments of the present invention will be described below with reference to more specific examples.

(Embodiment 1) In this embodiment, in the liquid crystal panel 100 shown in FIG. 1, a transparent electrode (pixel electrode 18) is used.
And the transparent electrode 22) on the opposite side so that the film thickness is 1 over the entire surface of the active matrix substrate 1 and the opposite substrate 2.
It is set to 0 nm or more and 50 nm. As a result, the absorption of light by the transparent electrode film is reduced to less than half, and the heat generated thereby is reduced to less than half, compared to the conventional liquid crystal panel in which the thickness of the transparent electrode film is set to 100 nm to 200 nm. can do.

(Second Embodiment) As in the first embodiment,
In the configuration in which the thin transparent film is provided on the entire surfaces of the active matrix substrate 1 and the counter substrate 2, the drain electrode 16 and the pixel electrode 18 of the pixel transistor 20 are provided.
To reduce the aspect ratio of the contact hole 18a provided in the interlayer insulating film 17 for connecting with, or to provide the contact hole 18a with a taper (inclination) by wet etching the interlayer insulating film 17, or A step as shown in FIG. 4C is formed in the contact hole 18a by etching the insulating film 17 twice, and the drain electrode 16 and the pixel electrode 1 are formed.
It is necessary to make the connection state with 8 good.

Therefore, in the second embodiment, as shown in FIGS. 7A and 7B, in the contact hole 18a portion connecting the pixel electrode 18 and the drain electrode 16,
The film thickness of the pixel electrode 18 is increased.

The method of manufacturing the active matrix substrate 1 of this embodiment will be described below. Here, since the steps before the pixel electrode formation (up to the step of forming the contact hole of the interlayer insulating film) are the same as the conventional one,
The description is omitted.

First, an ITO film having a thickness of 80 nm to 500 nm is formed by sputtering on the substrate 11 having the contact holes 18a formed in the interlayer insulating film 17. Next, a photoresist film is formed at least in the contact hole 18a portion by a photolithography method, and half etching is performed by dry etching. As shown in FIG. 7B, the contact hole 18a is formed.
It is possible to form the pixel electrode 18 in which the thickness of the portion is 80 nm to 500 nm and the thickness of the other portions is 10 nm to 50 nm.

In half-etching, reproducibility and uniformity of etching rate are important, and a liquid crystal panel for direct view using a large glass substrate (recently, meter size) requires high technology, but for projection use. In the liquid crystal panel of (1), since a small substrate (for example, 6 inch wafer or 8 inch wafer) is generally used, it can be controlled relatively easily.

Also, for the transparent electrode 22 on the counter substrate side, if necessary, an ITO film can be formed thick in advance, and only a necessary portion can be thinned by half etching. For example, since it is preferable to make the film thickness of the opposite transparent electrode 22 thick at the connecting portion between the opposite transparent electrode 22 and the active matrix substrate 1, the other portions are half-etched to make the film thin. can do.

Further, a metal film (or an intermetallic compound film)
/ ITO film is formed, and as shown in FIG. 7C, the metal film in the pixel opening is etched to form the contact hole 18
By leaving the metal film (or the intermetallic compound film) 28 in the portion a, the thickness of the pixel electrode 18 is set thin in the pixel opening and the connection between the pixel electrode 18 and the drain electrode 16 is improved. You can

In this case, selection of the material of the metal film (or intermetallic compound film) is important, and it is not preferable to use, for example, a commonly used Al film. This is Al
This is because the ITO film is reduced and blackened during film formation, and the absorptance of incident light increases. In order to prevent this problem, a compound by reactive sputtering such as Al / TiN or Al / TiO can be provided as a barrier layer. Alternatively, in the case of an Al / ITO film, for example, after the Al film is etched, the ITO film may be light-etched to remove the reduced transmittance-decreasing surface layer. In addition,
Other than the Al film, a W, TiW, WSi, Cr film or the like can be similarly used.

(Embodiment 3) In a normal liquid crystal panel, incident light is not applied only to the pixel openings, but also to the source bus lines and the light shielding film. Generally, these are made of a metal film, and at least the uppermost surface is often made of a material having a low reflectance (high absorptance) such as W or TiW in many cases. A film having a high reflectance but a low heat resistance, such as an Al film, is not used alone or on the uppermost surface. For small LCD panels,
Since the ratio of the pixel openings is 40% to 80%, a sufficient effect may not be obtained only by reducing the light absorption by the transparent electrode as in the first and second embodiments.

Therefore, in the third embodiment, as shown in FIG. 8, the counter substrate 2 is provided with the lens 30 for condensing the incident light at the pixel opening. Such a configuration in which the lens 30 is provided is generally used in a liquid crystal panel for projection applications.

By providing the lens 30 as described above, the light radiated to the liquid crystal panel is concentrated on the pixel opening portion, so that the light absorption by the source bus line or the like as described above can be almost ignored. Therefore, it is most suitable for the liquid crystal panel of the present invention that suppresses heat generation due to absorption of light and reduces the temperature rise of the liquid crystal panel.

If necessary, as shown in FIG. 9, the pixel electrode 18 in the region 40 where the incident light is not irradiated may not be half-etched and the film thickness may be increased.

As for the counter substrate side transparent electrode 22, as shown in FIG. 10, if necessary, the transparent electrode film is thickened without half-etching in the region 22b which is not irradiated with light. The film thickness can be reduced by performing half etching only on the opening 22a. However,
As shown in FIG. 8, on the counter substrate 2 side, since the lens 30 is in the middle of focusing light, the area of the screen portion where the incident light is not irradiated is reduced.

In FIG. 8, the lens 30 is set to 1 for each pixel.
Although the structure corresponding to the pair 1 is shown, the arrangement structure of the lens is not limited to this, and any arrangement structure capable of converging incident light to the opening portion of the pixel can obtain the same effect. You can

[0082]

As described above, according to the present invention,
It is possible to prevent the light emitted to the liquid crystal panel from being absorbed and suppress the rise of the panel temperature, so that the operation of the liquid crystal can be stabilized. Further, it is possible to realize a projection type liquid crystal display device which does not require a large-scale cooling mechanism as in the prior art which focuses on heat dissipation. In particular, in the future, in order to further increase the screen illuminance in the projection type liquid crystal display device, it is considered that the intensity of light irradiated on the liquid crystal panel will increase, and the present invention is a very effective technique.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a main part of an active matrix type liquid crystal panel.

FIG. 2 is a top view showing a configuration of one pixel in an active matrix substrate.

3A is an equivalent circuit diagram showing a circuit configuration for one pixel of a liquid crystal panel, FIG. 3B is an equivalent circuit diagram showing a circuit configuration along a certain gate bus line, and FIG. )
[Fig. 4] is an equivalent circuit diagram in which only the counter substrate side is extracted in (b).

4A and 4B are cross-sectional views showing a state of a connection portion between a pixel electrode and a drain electrode, and FIG. 4C is a schematic view showing another example of the connection portion.

FIG. 5 is a cross-sectional view showing a growth state of an ITO film.

FIG. 6 is a graph showing the relationship between the film thickness of the ITO film and the transmittance and absorptance of visible light.

FIG. 7A is a top view showing the configuration of one pixel in the active matrix substrate of the second embodiment,
(B) And (c) is a sectional view of the AA 'part of (a), respectively.

FIG. 8 is a cross-sectional view showing the configuration of one pixel in the liquid crystal panel of Embodiment 3.

FIG. 9 is a top view showing the configuration of one pixel in the active matrix substrate of the third embodiment.

FIG. 10 is a top view showing the configuration of a counter substrate according to a third embodiment.

[Explanation of symbols]

1 Active Matrix Substrate 2 Counter Substrate 3 Liquid Crystal Layers 11 and 21 Substrate 12 Si Layer 13 Gate Insulating Film 14 Gate Electrode (Gate Bus Line) 14a Cs Bus Line 15 Source Electrode (Source Bus Line) 15a, 16a, 18a Contact Hole 16 Drain Electrode 17 Interlayer insulating film 18 Pixel electrodes 19 and 23 Alignment film 20 Pixel transistor 22 Counter substrate side transparent electrode 22a Counter substrate side transparent electrode thin region (pixel opening) 22b Counter substrate side transparent electrode thick region 28 Metal Film (intermetallic compound film) 30 Lens 31 Liquid crystal capacitance 32 Cs capacitance 40 Area where the thickness of the transparent electrode is large

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03B 21/14 G03B 21/14 ZF term (reference) 2H088 EA12 HA02 HA08 HA25 HA28 MA20 2H091 FA29X FD04 GA02 GA13 LA04 MA07 2H092 GA12 HA04 JA24 JA46 JB01 MA17 NA25 PA07 RA05 2K103 AA05 AB10 BB02 DA03

Claims (14)

[Claims] 1. A liquid crystal panel in which a pair of substrates each provided with a transparent electrode are opposed to each other with a liquid crystal layer in between, and at least one of the substrates has a thickness of 1 or less.
A liquid crystal panel having a thickness of 0 nm or more and 50 nm or less. 2. In a liquid crystal panel in which a pair of substrates each provided with a transparent electrode are opposed to each other with a liquid crystal layer interposed therebetween, at least the transparent electrode provided on one of the substrates has a thickness of a light incident path portion, A liquid crystal panel that is thinner than the other parts. 3. The liquid crystal panel according to claim 2, wherein the transparent electrode has a thickness of a light incident path portion of 10 nm or more and 50 nm or less. 4. The liquid crystal panel according to claim 2, wherein the transparent electrode has a thickness of 80 nm or more and 500 nm or less in a portion other than the light incident path portion. 5. In a liquid crystal panel in which a pair of substrates each provided with a transparent electrode are opposed to each other with a liquid crystal layer interposed therebetween, at least one of the substrates has a thickness of 1 or less.
A liquid crystal panel having a thickness of 0 nm or more and 50 nm or less, and a metal film or an intermetallic compound film is laminated on the transparent electrode in a portion other than the light incident path portion. 6. The active matrix substrate of the pair of substrates includes a plurality of scanning wirings and a plurality of signal wirings intersecting with each other, switching elements arranged in a matrix shape near each intersection of both wirings, and An active matrix substrate transparent electrode connected to the switching element is provided, and a scanning signal for turning on / off the switching element is supplied from the scanning wiring, and the active matrix is also transmitted from the signal wiring via the switching element. A signal is supplied to the substrate-side transparent electrode, the counter-substrate-side transparent electrode is provided on the counter-substrate, and matrix-shaped pixels are provided at the facing portions of the active matrix substrate-side transparent electrode and the counter-substrate-side transparent electrode. The liquid crystal panel according to any one of claims 1 to 5, which is configured. 7. The active matrix substrate is configured such that the switching element and the active matrix substrate side transparent electrode are connected through a contact hole, and the active matrix side transparent electrode has a thickness in the contact hole portion. The liquid crystal panel according to claim 6, which has a thickness of 80 nm or more and 500 nm or less. 8. In the active matrix substrate, the switching element and the active matrix substrate side transparent electrode are connected through a contact hole, and the thickness of the active matrix substrate side transparent electrode is in the contact hole portion. Is 10 nm or more and 50 nm
7. The liquid crystal panel according to claim 6, wherein a metal film or an intermetallic compound film is laminated on the transparent electrode on the active matrix substrate side. 9. The counter substrate is electrically connected to the active matrix substrate, and the thickness of the counter substrate-side transparent electrode is 80 nm or more 500 at the connection portion.
The liquid crystal panel according to claim 6, which has a thickness of not more than nm. 10. The counter substrate is electrically connected to the active matrix substrate, and the thickness of the counter substrate side transparent electrode is 10 nm or more and 50 nm or more at the connecting portion.
7. The liquid crystal panel according to claim 6, wherein the liquid crystal panel has a thickness of not more than 10 nm, and a metal film or an intermetallic compound film is laminated on the counter substrate-side transparent electrode. 11. The liquid crystal panel according to claim 1, wherein the counter substrate is provided with an incident light condensing lens corresponding to each pixel. 12. A method for manufacturing a liquid crystal panel according to claim 2, wherein a transparent conductive film having a thickness of 80 nm or more is formed on at least one substrate.
A method for manufacturing a liquid crystal panel, which is formed to a thickness of 00 nm or less, and the transparent conductive film in the light incident path portion is etched to a thickness of 10 nm to 50 nm. 13. The method of manufacturing a liquid crystal panel according to claim 3, wherein a transparent conductive film having a thickness of 10 nm or more is formed on at least one substrate.
A method for manufacturing a liquid crystal panel, which is formed to a thickness of 0 nm or less, and a metal film or an intermetallic compound film is laminated on the transparent conductive film, and then the metal film or the intermetallic compound film in the light incident path portion is removed by etching. 14. A projection type liquid crystal display device for irradiating the liquid crystal panel according to claim 1 with light from a light source to project and display an image on a screen.