JP2003322863A - Device having liquid crystal display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device having liquid crystal panel on which a fact that display is adversely affected due to unevenness of cell gaps is suppressed. <P>SOLUTION: In a liquid crystal cell by which a liquid crystal is sealed and the cell gaps are held by a seal material 101 without using a scattering spacer, interference fringes 103 in the concentric shapes are inevitably formed, however, a surrounding driving circuit is provided in an area where the interference fringes 103 exist and a pixel matrix circuit 105 is arranged in an area where the interference fringes 103 do not exist. Thus, a fact that the display is influenced by the cell gap is suppressed by determining positions of circuit arrangement by using the interference fringes as parameters. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The invention disclosed in this specification includes:
The present invention relates to a liquid crystal panel that can perform excellent display.
Further, the present invention relates to a device using such a liquid crystal panel.

[0002]

2. Description of the Related Art In an active matrix type liquid crystal display device, an active matrix circuit, a circuit for driving the circuit (referred to as a peripheral drive circuit) and other peripheral circuits (various circuits required for a liquid crystal panel) are the same. A structure in which a TFT is integrated on a substrate is known. This configuration is called a peripheral drive circuit integrated type.

This configuration is (1) The entire structure can be simplified and downsized. (2) The manufacturing process can be simplified. (3) It is advantageous for low power consumption. It has such characteristics.

Particularly in a portable information processing terminal or a projector type liquid crystal panel, it is required to reduce the size of the liquid crystal panel, and for that purpose, it is of great significance to integrate a peripheral drive circuit.

[0005]

According to the knowledge of the present inventors, when the liquid crystal panel is miniaturized, the existence of the spacer that determines the thickness of the liquid crystal layer becomes a problem.

For example, in a small liquid crystal panel having a size of 2 inches or less, which is used for a projector or the like,
Since the size of the pixel is about 30-40 μm square or less,
The shadow of the spacer having a diameter of several μm existing in the unit pixel affects the display.

To solve this problem, a cell gap (corresponding to the thickness of the liquid crystal layer) is provided by a sealant (sealing material) arranged so as to surround the pixel region (pixel matrix region) without using a spacer. It is considered that the structure is such that it holds).

FIG. 2 (A) schematically shows a transmissive liquid crystal panel having a screen size of 1.4 inches diagonal, which was prototyped for observing the cell gap.

This liquid crystal panel is a prototype, and no active matrix circuit or peripheral drive circuit is formed.

In FIG. 2A, a reference numeral 21 is a sealing material, and liquid crystal is sealed inside the sealing material. This liquid crystal panel has a structure in which a cell gap is maintained by a material called a filler contained in the sealing material 21 and having a predetermined size.

Further, this liquid crystal panel does not utilize a spacer for holding the cell gap. That is,
There is no means for maintaining the cell gap other than the area where the sealing material is provided.

Reference numeral 24 is a liquid crystal inlet. The liquid crystal injection port is closed with an ultraviolet curable resin or the like after the liquid crystal is injected.

A glass substrate 24 constitutes a liquid crystal panel. Here, a state where two glass substrates are overlapped is shown. (Liquid crystal is held between these two glass substrates)

In this configuration, since the spacer does not exist in the pixel area (in this case, the inside of the sealing material 21), the existence of the spacer does not adversely affect the image quality.

However, when the liquid crystal panel shown in FIG. 2 (A) is irradiated with monochromatic light, it is concentric toward the center of the liquid crystal panel from the region where the sealing material is provided as shown in FIG. 2 (B). Interference fringes are observed.

The interference fringes indicate that the cell gaps are not uniform. That is, it shows that the cell gap is narrowed at the center of the liquid crystal panel.

FIG. 3 shows a schematic diagram in which this state is extremely emphasized. In FIG. 3, a pair of substrates 20 is provided by the sealing material 21.
The state in which the liquid crystal 22 is sandwiched and held between 1 and 202 is shown.

In the central portion 203 of the liquid crystal panel, the cell gap d is shown to be small.

The interference fringes shown in FIG. 2B appear in the portion 204 where the positional change of the cell gap is large.
In addition, since the cell gap of the central portion 203 of the liquid crystal cell hardly changes, interference fringes do not appear there.

The interference fringes shown in FIG. 2B are caused by the interference of light reflected from the surface of the substrate forming the liquid crystal cell.

The principle of generation of interference fringes will be described with reference to FIG. FIG. 4 shows a state in which a pair of glass substrates 41 and 42 are opposed to each other in a state where the interval (corresponding to the cell gap) is not constant.

When monochromatic light enters in such a state, the light reflected on the back surface of one glass substrate 41 interferes with the light reflected on the surface of the other glass substrate 42. (There are other interferences, but I think this way to simplify the discussion.)

If the cell gap d is constant, that is, d ₁ =
If d ₂ = d ₃ , the interference state is the same in all parts, so no bright and dark stripe pattern appears.

However, if the gap d is different depending on the place, the light and dark conditions are different depending on the place, and a striped pattern is generated according to the changing state of the gap d.

The condition under which the striped pattern occurs is estimated to be the case where there is a difference of about λ / 2 in the difference in cell gap between places.

First, assuming that the cell gap in the first bright portion is d _{1 and the} cell gap in the adjacent first bright portion is d ₂ , the difference between the optical path lengths at these two locations is the cell gap. Considering that light goes back and forth between them, it becomes 2 (d ₂ −d ₁ ).

The first bright condition and the second bright condition are satisfied when the two optical path lengths differ by about the wavelength λ of the incident light.

Therefore, λ = 2 (d ₂ −d ₁ ) is established. That is, the difference (d ₂ −d ₁ ) in the cell gap between the two bright portions is about λ / 2.

The wavelength of incident light is generally 500 nm to 55 nm.
Since it is about 0 nm (0.5 μm to 0.55 μm), the difference in cell gap is estimated to be about 0.25 μm.

Actually, the state of light reflection on the glass surface is not simple (it becomes complicated when an insulating film, a conductive film or the like is formed on the surface of the glass substrate). ), And when the liquid crystal material is filled, the wavelength of light in the liquid crystal material is λ / n depending on the refractive index n of the liquid crystal material, so the difference in cell gap is smaller than the approximate value. It will be.

In any case, a striped pattern is observed when the cell gap changes in the order of a fraction of visible light.

Generally, the cell gap of a liquid crystal panel is 1 μm.
It is set to about m to 5 μm. This value is determined by the operation mode and the liquid crystal material used.

However, if the cell gap of the liquid crystal panel deviates from the set value by 10% or more, the transmittance of light passing through the liquid crystal changes by about 20% or more of the set value.

Therefore, for example, when a liquid crystal panel in which interference fringes as shown in FIG. 2B are observed is manufactured with a cell gap of 3 μm and the entire inside of the sealing material is used for screen display, A cell gap difference of the order of μm occurs between the peripheral portion and the central portion.

This means that the display state is significantly different between the peripheral portion and the central portion of the screen. (Actually, screen displays with different image quality are observed like donuts)

An object of the invention disclosed in this specification is to solve the problem of nonuniformity of the cell gap in the above-described liquid crystal panel.

[0037]

The invention disclosed in this specification is premised on the occurrence of interference fringes on a panel surface when a liquid crystal panel is manufactured, and a configuration incorporating the existence of the interference fringes as a design parameter. It is characterized by

Specifically, the pixel matrix area is arranged avoiding the area where the interference fringes are generated, and the peripheral drive is arranged in the area where the interference fringes are generated.

By doing so, it is possible to prevent the liquid crystal panel in which interference fringes are generated from being adversely affected by the presence of the interference fringes in the display. In addition, since the arrangement of the circuits in the liquid crystal cell can be made wasteful, the device can be miniaturized as much as possible.

The area in which the peripheral circuits are arranged is an area in which the cell gap changes greatly depending on the location.
Although this may adversely affect the operation of the circuit, unless the pressure is directly applied to the peripheral driving circuit itself, the change in the cell gap where the interference fringes occur does not matter. .

One of the inventions disclosed in this specification has a structure in which liquid crystal is sandwiched and held between a pair of substrates, and the liquid crystal is sealed in a predetermined region by a sealing material. The thickness of the liquid crystal layer is maintained by the liquid crystal layer, and the liquid crystal layer has nonuniformity in thickness where interference fringes appear, and an active matrix circuit is provided in a region where the interference fringes do not appear. Is characterized in that a peripheral circuit is provided in a region where appears.

In the above structure, the kind of liquid crystal material and the operation mode are not particularly limited.

The interference fringes are generated by irradiating the liquid crystal panel with monochromatic light.

The peripheral circuit also includes a circuit for simply driving the active matrix circuit.

According to another aspect of the present invention, a liquid crystal is sandwiched and held between a pair of substrates, the liquid crystal is sealed in a predetermined area by a sealing material, and the thickness of the liquid crystal layer is sealed by the sealing material. Is held, the liquid crystal layer has non-uniformity in thickness where interference fringes appear, the interference fringes have a concentric shape, and the inside of the region where the interference fringes having the concentric shape appears Is provided with an active matrix circuit, and a peripheral circuit is provided in a region where the interference fringe appears.

According to another aspect of the invention, a liquid crystal is sandwiched and held between a pair of substrates, the liquid crystal is sealed in a predetermined region by a sealing material, and the thickness of the liquid crystal layer is sealed by the sealing material. Is held, the liquid crystal layer has a non-uniformity in thickness where interference fringes appear, the interference fringes have a concentric shape, and a region in which no interference fringes appear at the center of the concentric shape Is provided with an active matrix circuit, and a peripheral circuit is provided in a region where the interference fringe appears.

The above inventions are preferably applied to those in which the thickness of the liquid crystal layer is held only by the sealing material.
That is, the invention disclosed in this specification is particularly effective when a means for holding the thickness of the liquid crystal layer is not provided inside the sealing material.

This is because a concentric interference fringe as shown by 102 in FIG. 1 is particularly likely to occur.

The concentric shape means a shape in which a plurality of figures having substantially the same center are present with different sizes. For example, a state in which there are a plurality of figures each having a substantially quadrangular shape (rounded corners) as shown by 102 in FIG.

In the invention disclosed in this specification, the liquid crystal panel may be a transmissive type or a reflective type.

[0051]

BEST MODE FOR CARRYING OUT THE INVENTION In the invention disclosed in this specification, the existence of interference fringes observed due to the nonuniformity of the cell gap (corresponding to the thickness of a liquid crystal layer) of a liquid crystal panel is used as a design parameter. It is characterized in that it is incorporated and utilized for the structure of the liquid crystal cell.

Specifically, in the liquid crystal panel as shown in FIG. 1, the active matrix circuit 105 is arranged inside the area where the interference fringes 102 exist, and the peripheral circuit is arranged in the area where the interference fringes 102 exist. .

By doing so, even if the structure having the interference fringes 102 is generated, its presence can be prevented from appearing in the display.

The present invention is a sealing material 1 as shown in FIG.
01 is particularly effective for a liquid crystal panel having a structure that determines the thickness (cell gap) of the liquid crystal layer.

[0055]

EXAMPLES Example 1 FIG. 1 shows an outline (top view schematic diagram) of a liquid crystal panel utilizing the invention disclosed in this specification.

In the structure shown in FIG. 1, 101 is a sealing material. In the liquid crystal panel shown in FIG. 1, the cell gap is maintained by a material called a filler contained in the sealing material 101. No spherical spacer or the like is used in the pixel matrix 105.

Liquid crystal is filled inside the sealing material 101. Reference numeral 106 denotes a liquid crystal injection port, which is closed by an ultraviolet curable resin in the illustrated state.

Reference numeral 102 is a pattern of interference fringes that appear when visible light is irradiated. What is important in the configuration shown in FIG. 1 is that the pixel matrix region 105 is not provided in the region where the striped pattern appears, but is provided in the region where the striped pattern does not exist.

That is, since the area where the interference fringes are present is a place where the change in the cell gap is large (the cell gap is changed to such an extent that the display is affected), the peripheral circuit is not used as a screen and the interference fringes are not used. Peripheral circuits, which are optically dead spaces, are arranged in the existing areas.

In FIG. 1, reference numerals 103 and 104 denote peripheral drive circuits for driving the pixel matrix 105.
Here, since a circuit including a shift register, a switch, and a buffer is used as a peripheral circuit, the peripheral circuit is referred to as a peripheral drive circuit.

The peripheral drive circuits 103 and 104 are provided in the region 102 where the striped pattern is formed.

In the region where the striped pattern is formed, the cell gap changes at a distance of about 1/2 or less of visible light in the striped distance. That is, the change is on the order of about 0.25 μm or less.

In this situation, it can be considered that the thickness of the liquid crystal layer also changes in the order of about 0.25 μm or less.

Therefore, in the region where the stripe pattern exists, it can be considered that the thickness of the liquid crystal layer changes in the order of about 0.25 μm or more.

The transmittance of light transmitted through the liquid crystal layer greatly changes depending on the thickness of the liquid crystal layer. In the region where the striped pattern is dense, the thickness of the liquid crystal layer is also changing rapidly. Therefore, in this region, the light transmittance also greatly changes depending on the location.

In the structure shown in FIG. 1, the pixel matrix region is arranged so as to avoid the region where the thickness of the liquid crystal layer is largely changed (that is, the region where the stripe pattern is formed).

By doing so, it is possible to eliminate the influence on the screen display due to the fact that the thickness of the liquid phase layer largely changes depending on the location.

The striped pattern shown by 102 is basically inevitable when the cell gap is held only by the sealing material. (There is also a method of using a special glass substrate with high rigidity, but it is expensive and not practical)

Therefore, it is useful to adopt the circuit arrangement as shown in this embodiment on the assumption that there is a cell gap state in which the interference fringes 102 are generated.

[Embodiment 2] In this embodiment, an example of an apparatus provided with a liquid crystal panel utilizing the present invention will be shown.

As such a device, a video camera,
Digital still camera, head mounted display,
Examples include car navigation, personal computers, personal digital assistants (mobile computers, mobile phones, etc.).

FIG. 5A shows a mobile computer, which has a main body 2001, a camera section 2002, an image receiving section 2003, operation switches 2004, a liquid crystal panel 2005.
Composed of.

The liquid crystal panel 2005 may be of a reflective type or a transmissive type.

FIG. 5B shows a head mounted display, which includes a main body 2101, a reflective liquid crystal panel 2102,
The band unit 2103 is included.

FIG. 5C shows a front projection type liquid crystal panel. In this device, light from a light source 2202 is guided to a reflective liquid crystal panel 2203 by an optical system 2204, and an image optically modulated by the liquid crystal panel 2203 is enlarged by the optical system 2204 and projected on a screen 2205.

The projection of this form is
In addition to 01, a screen 2205 is required.

FIG. 5D shows a mobile phone having a main body 230.
1, audio output unit 2302, audio input unit 2303, liquid crystal panel 2304, operation switch 2305, antenna 230
It is composed of 6.

FIG. 5E shows a video camera, which is a main body 2
401, liquid crystal panel 2402, voice input unit 2403, operation switch 2404, battery 2405, image receiving unit 24.
It is composed of 06.

FIG. 5F shows an apparatus called a rear projection type. In this device, the light emitted from the light source 2502 is optically modulated by the reflection type liquid crystal panel 2503 by the polarization beam splitter 2504, reflected by the reflectors 2505 and 2506, and projected on the screen 2507. In this type of device, a screen 2507 is arranged on a main body 2501.

[0080]

By utilizing the invention disclosed in this specification, it is possible to provide a liquid crystal panel in which even if there is nonuniformity in the cell gap, the influence thereof does not appear in the display.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a state where a liquid crystal panel of an example is viewed from above.

FIG. 2 is a diagram showing a structure of liquid crystal.

FIG. 3 is a schematic diagram showing a state of a cell gap of a liquid crystal panel.

FIG. 4 is a diagram showing a principle of generation of interference fringes.

FIG. 5 is a diagram showing an apparatus using a liquid crystal panel.

[Explanation of symbols]

101 sealing material (sealing material) 102 interference fringe 103 peripheral circuit 104 peripheral circuit 105 active matrix circuit (pixel matrix circuit) 106 liquid crystal inlet

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09F 9/35 G09F 9/35 5C094 H04N 5/66 102 H04N 5/66 102A F term (reference) 2H088 EA12 FA02 FA04 HA05 HA08 KA02 MA04 MA06 MA17 2H089 LA12 LA13 LA15 LA16 LA41 LA49 NA24 PA15 QA04 QA14 SA01 TA07 UA05 2H092 GA59 JA24 NA03 PA03 PA04 RA05 2K103 AA05 AB10 BB02 5C058 AA06 AB01 BA35 FA01 CA35 DA02 FA43 CA02 BA03 BA43

Claims (3)

[Claims] 1. A pair of substrates, a sealing material, and a liquid crystal sealed inside the sealing material between the pair of substrates,
An active matrix circuit and a driving circuit for driving the active matrix circuit are provided, and a cell gap, which is a distance between the pair of substrates, has nonuniformity necessary for appearance of interference fringes. A device having a liquid crystal panel, wherein a cell gap is maintained, the active matrix circuit is provided in a region where the interference fringes do not appear, and the drive circuit is provided in a region where the interference fringes appear. 2. A pair of substrates, a sealant containing a filler, a liquid crystal sealed inside the sealant between the pair of substrates, an active matrix circuit, and a drive circuit for driving the active matrix circuit. The cell gap, which is the distance between the pair of substrates, has a non-uniformity necessary for appearance of interference fringes, the cell gap is held by a sealant containing the filler, and the interference fringes do not appear. A device provided with a liquid crystal panel, wherein the active matrix circuit is provided in a region, and the drive circuit is provided in a region where the interference fringes appear. 3. An apparatus having a liquid crystal panel, wherein the apparatus according to claim 1 or 2 is a projector.