JP2000098378A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal display device in which a screen display can be viewed without consuming electric power of a light source such as a frontlight even in a dark place. SOLUTION: In the liquid crystal display device provided with a reflection type liquid crystal display panel 10 having a polarizing plate 2 and a reflection layer 7, a black matrix 4 is selectively provided around pixel regions on the surface of a transparent glass substrate 3 opposite to a liquid crystal layer 6. Furthermore, light storage layers 1 are laminated on the surfaces of the black matrix 4 on the side of the liquid crystal layer 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type liquid crystal display device used as a display of an information processing device such as a personal computer.

[0002]

2. Description of the Related Art For example, a liquid crystal display device of the active matrix type is provided with a non-linear element (switching element) corresponding to each of a plurality of pixel electrodes arranged in a matrix. Since the liquid crystal in each pixel is theoretically always driven (duty ratio 1.0),
The active method has better contrast than the so-called simple matrix method that adopts the time-division driving method,
In particular, it is becoming an indispensable technology for color liquid crystal display devices. A typical switching element is a thin film transistor (TFT).

Incidentally, an active matrix type liquid crystal display device using thin film transistors is disclosed in, for example, Japanese Patent Application Laid-Open No. 63-309921 or "1.
2.5-inch active matrix color liquid crystal display ", Nikkei Electronics, pp. 193-210, December 1986
March 15, published by Nikkei McGraw-Hill, Inc.

[0004] Liquid crystal display devices have started to be widely used as display terminals for information processing equipment (OA equipment) such as portable mobiles and notebook personal computers because of their features of being thin, lightweight, and having high image quality comparable to cathode ray tubes.

A reflection type liquid crystal display device (ie, a liquid crystal display module) includes a transparent insulating substrate made of, for example, two sheets of glass provided with a display electrode on at least one of the opposing surfaces (inner surfaces) of the device. The two substrates are bonded together with a liquid crystal sealing material provided in a frame shape (b-shape) on the peripheral edge between the two substrates, and both are bonded through a liquid crystal sealing opening provided in a part of the sealing material. A liquid crystal is sealed inside the sealant between the substrates, and a polarizing plate that transmits only a certain amount of polarized light is provided outside the substrate on the display screen side (that is, the screen observation side). A liquid crystal display panel provided with a reflective layer on the opposite surface side (ie, a liquid crystal display device, LCD: Liquid Crystal Display (Liquid Crystal Display))
d Crystal Display), a driving circuit board that is disposed outside the outer peripheral portion of the liquid crystal display panel and applies a voltage corresponding to a display image signal to the electrodes, and a liquid crystal display panel and the like are housed.
It is composed of a case formed of a plastic mold or the like to be held, a case accommodating the above members, and a display window opened.

For example, in an active matrix vertical electric field type liquid crystal display panel, one of two transparent insulating substrates disposed to face each other with a liquid crystal layer interposed therebetween extends in the x direction on the surface facing the liquid crystal layer side. And a plurality of data lines extending in the y direction and juxtaposed in the x direction via the gate line and the insulating film are formed. A unit pixel region is formed in a region surrounded by lines, and each of the pixel regions includes a thin film transistor and a pixel electrode.

These pixel electrodes are supplied with a video signal voltage from a data line through a thin film transistor which is turned on by the supply of a scanning signal voltage from a gate line,
As a result, an electric field is generated between the common pixel electrode formed on the opposing surface of the other opposing substrate, and the electric field causes light transmission in the liquid crystal layer interposed between the pixel electrode and the common pixel electrode. The display is modulated and a predetermined display is performed.

FIG. 6 is a schematic sectional view of a main part of an example of a conventional reflection type liquid crystal display panel.

In FIG. 6, reference numeral 10 denotes a liquid crystal display panel;
Is a polarizing plate, 3 is a transparent glass substrate, 4 is a black matrix, 5 is a color filter, 6 is a liquid crystal layer, 7 is a reflective layer, 8
a and 8d are light paths. In this figure, the other transparent glass substrate, display electrode, thin film transistor and the like are not shown.

[0010]

In the conventional liquid crystal display panel 10 shown in FIG. 6, as shown by a light path 8a,
When light enters the liquid crystal display panel 10, the light is reflected by the reflection layer 7 and emitted again, so that the display on the screen formed on the liquid crystal display panel 10 can be viewed. However, when the liquid crystal display device including the reflective liquid crystal display panel 10 is used in a dark room, the light path is cut off, and the display on the screen cannot be seen.

In a reflection type liquid crystal display device having a light source (front light) on a display screen side (ie, a screen observation side) even in a dark place, if the light source is used, the display screen can be viewed. However, the power consumption of the light source is large compared to the power consumption of the liquid crystal driving circuit, and when a portable information processing device is driven by a battery, the use time of the device is limited, which is inconvenient.

An object of the present invention is to provide a reflection type liquid crystal display device which can display a display on a screen without consuming power for a light source such as a front light even in a dark place.

[0013]

In order to solve the above-mentioned problems, the present invention is characterized in that a reflection type liquid crystal display device is provided with a light storage layer for storing light in a region other than a pixel region.

[0014] Further, the two superposed at a predetermined interval.
Sheet substrates, a liquid crystal layer sealed between the two substrates, a display electrode provided on at least one of the opposing surfaces of the two substrates,
A liquid crystal display device provided with a reflective liquid crystal display panel including a polarizing plate provided on an outer surface side of the first substrate on a display screen side and a reflective layer provided on a facing surface side of the second substrate. And a light storage layer for storing light is provided in a region other than the pixel region.

Further, a black matrix is provided on a surface of the first substrate facing the liquid crystal layer, and the luminous layer is provided on a surface of the black matrix on the liquid crystal layer side.

In the liquid crystal display device of the present invention, light is accumulated in the luminous layer in a bright place, and in a dark place,
Light is emitted from the light storage layer in which the light is stored, enters the liquid crystal display panel, is reflected by the reflection layer, and is emitted again, so that the display on the screen can be viewed. That is, even in a dark place, light can be emitted without using power, and the display on the screen can be viewed without consuming power for a light source such as a front light.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the drawings described below, those having the same functions are denoted by the same reference numerals, and the repeated description thereof will be omitted.

FIG. 1 is a schematic sectional view of a main part of a reflection type liquid crystal display panel according to an embodiment of the liquid crystal display device of the present invention.
FIG. 1A shows a case where there is external light (that is, when a bright place or a front light is used), and FIG. 1B shows a case where there is no external light (that is, a dark place).

In FIG. 1, reference numeral 10 denotes a liquid crystal display panel, 2
Is a polarizing plate, 3 is a transparent glass substrate, 4 is a black matrix, 5 is a color filter, 6 is a liquid crystal layer, 7 is a reflective layer, 1
Is a light storage layer, and 8a, 8b, 8c are light paths.

FIG. 2 is a schematic cross-sectional view of a main part showing the reflection type liquid crystal display panel of FIG. 1 more specifically.

In FIG. 2, 5R, 5G, and 5B are, for example, red, green, and blue color filters of three primary colors, 11 is a protective film of the color filter, 12 is a common transparent pixel electrode, and 7 is a reflective layer including a TFT electrode and the like. is there.

In FIGS. 1 and 2, the other transparent glass substrate facing the transparent glass substrate 3, the transparent electrode for display provided on the opposite substrate, the thin film transistor and the like are not shown (FIGS. 4 and 5). 5).

In the present embodiment, the luminous layer 1 is formed on the black matrix 5 outside the pixel area (the lower side in the figure; the side opposite to the screen observation side, ie, the liquid crystal layer 6 side). As the phosphorescent material, various known materials can be used. For example, the phosphorescent material is made by mixing a rare earth element such as europium with an alkaline earth metal such as strontium and barium. As a method for forming the phosphorescent material, adhesion, pressure bonding, vapor deposition,
Various methods such as sputtering, printing, coating and sedimentation coating can be used.

As shown in FIG. 1 (a), when the camera is used in a normal bright room, or when external light (natural light, illumination light, front light, etc.) exists such as when a front light is used, As shown in the light path 8a, when light enters the liquid crystal display panel 10, the light is reflected by the reflective layer 7 and emitted again, so that the display on the screen formed on the liquid crystal display panel 10 can be viewed. When the liquid crystal display device is used in a bright place, light is transmitted through a light path 8.
As shown in FIG. 2B, the light reaches the light storage layer 1 on the black matrix 5 and the external light is accumulated in the light storage layer 1.

As described above, when the conventional reflection type liquid crystal display device without the front light shown in FIG. 6 is used in a dark room, the light path is cut off and the display on the screen can be seen. Did not. However, in the reflection type liquid crystal display device of the present embodiment, when external light is cut off in a dark room or the like, as shown in a light path 8c of FIG.
When used in a bright room, light is emitted from the light storage layer 1 in which light is stored, enters the liquid crystal display panel 10, is reflected by the reflection layer 7 and is emitted again, so that the display on the screen is viewed (confirmed). It is possible.

As described above, in the reflection type liquid crystal display device of the present embodiment, the liquid crystal display panel 10 is illuminated by the light accumulated in the light storage layer 1 even in a dark place.
The display on the screen can be viewed without consuming power by a light source such as a front light.

For example, when a liquid crystal display device with a front light is used with the front light turned on in a dark place, when the capacity of the battery is reduced, the power supply before registration (save) of the document being created is performed. To prevent the light from being turned off, the luminous layer 1 is
Since the screen can be confirmed by the light emitted from, the registration of the document being created, the end work of the program of the liquid crystal display device,
Alternatively, a small amount of documentation can be created.

The reason that the luminous layer 1 is provided in the portion of the black matrix 5 outside the pixel area is that light emitted from the luminous layer 1 is directly emitted to the screen observation side of the liquid crystal display panel 10,
This is to prevent the display from being hindered.

FIGS. 3A to 3F are schematic sectional views showing steps of a method for manufacturing one of the substrates (on the display screen side) shown in FIGS.

First, as shown in FIG. 3A, a black matrix 4 is selectively formed in a portion around a pixel region on a transparent glass substrate 3.

Next, as shown in FIG. 3B, a luminous material is formed on the black matrix 4 by vapor deposition or sputtering, or a luminous paint is applied to selectively form the luminous layer 1. Form.

Next, as shown in FIG. 3C, a red filter 5R is formed in a predetermined pixel region by a known method.

Next, as shown in FIG. 3D, a green filter 5G is formed in a predetermined pixel area.

Next, as shown in FIG. 3E, a red filter 5B is formed in a predetermined pixel area.

Finally, as shown in FIG. 3 (f), a color filter protective film 11 and a common transparent pixel electrode 12 are formed on the color filters 5R, 5G and 5B.

Hereinafter, a more detailed structure of the liquid crystal display panel of the active matrix vertical electric field type reflection type color liquid crystal display device to which the present invention is applied will be described.

<< Outline of Matrix Section of Liquid Crystal Display Panel >>
FIG. 4 is a plan view showing one pixel of an active matrix vertical electric field type color reflection type liquid crystal display panel and its periphery.
FIG. 5 is a view showing a cross section taken along section line 5-5 in FIG. 4.

As shown in FIG. 4, each pixel has two adjacent scanning signal lines (gate signal lines or horizontal signal lines) GL.
And two adjacent video signal lines (drain signal lines or vertical signal lines) DL (in a region surrounded by four signal lines). Each pixel includes a thin film transistor TFT, a transparent pixel electrode ITO1, and a storage capacitor Cadd. The scanning signal lines GL extend in the left-right direction in FIG. Video signal line DL
Extend in the up-down direction and are arranged in a plurality in the left-right direction.

As shown in FIG. 5, a thin film transistor TFT and a transparent pixel electrode ITO1 are formed on the lower transparent glass substrate SUB1 side with respect to the liquid crystal layer LC, and a color filter FIL and a light shielding Black matrix pattern BM and phosphorescent layer AL
Are formed. Transparent glass substrates SUB1, SUB2
A silicon oxide film SIO formed by dipping or the like is provided on both surfaces.

The light-shielding film BM, the luminous layer AL, the color filter FIL, the protective film PSV2, and the common transparent pixel electrode I are provided on the inner surface (the liquid crystal LC side) of the upper transparent glass substrate SUB2.
TO2 (COM) and an upper alignment film ORI2 are sequentially laminated.

A polarizing plate and a phase difference plate POL + ISO are provided on the outer surface of the transparent glass substrate SUB1 on the display screen side, and the reflection layer RE is provided on the opposite surface side of the transparent glass substrate SUB2.
F is provided.

<< Black Matrix BM >> External light or front light is applied to the upper transparent glass substrate SUB2 side.
A black matrix (light-shielding film) BM is provided so as not to enter the mold semiconductor layer AS. The closed polygonal outline of the black matrix BM shown in FIG. 4 indicates an opening on the inside of which the black matrix BM is not formed. The black matrix BM is formed of, for example, an aluminum (Al) film or a chromium (Cr) film having a high light shielding property. In this embodiment, the chromium film is formed to a thickness of about 1300 ° by sputtering.

Therefore, the thin film transistors TFT1,
The i-type semiconductor layer AS of the TFT 2 is sandwiched between the upper and lower black matrices BM and the large gate electrode GT, so that external natural light or front light does not shine. The black matrix BM is formed in a grid around each pixel, and an effective display area of one pixel is partitioned by the grid. Therefore, the outline of each pixel is made clear by the black matrix BM, and the contrast is improved. That is, the black matrix BM has two functions of light shielding for the i-type semiconductor layer AS and black matrix.

The edge portion (the lower right portion in FIG. 4) on the root side of the rubbing direction of the transparent pixel electrode ITO1 is also shielded from light by the black matrix BM. Therefore, even if a domain is generated in the above portion, the domain is not visible. The display characteristics do not deteriorate.

The black matrix BM is also formed in a frame shape on the periphery of the liquid crystal display panel, and its pattern is formed continuously with the pattern of the matrix section shown in FIG. The black matrix BM in the peripheral portion is extended outside the seal portion SL, and prevents leakage light such as reflected light due to a mounting machine such as a personal computer from entering the matrix portion. On the other hand, the black matrix BM is about 0.3 to 1.0 m above the edge of the substrate SUB2.
m, and is formed so as to avoid the cutting region of the substrate SUB2.

<< Color Filter FIL >> The color filter FIL is formed in a stripe shape at a position facing the pixel by repeating red, green and blue. The color filter FIL is formed to be large so as to cover all of the transparent pixel electrode ITO1, and the black matrix BM is formed inside the periphery of the transparent pixel electrode ITO1 so as to overlap with the color filter FIL and the edge of the transparent pixel electrode ITO1. I have.

The color filter FIL can be formed as follows. First, a dye base such as an acrylic resin is formed on the surface of the upper transparent glass substrate SUB2, and the dye base other than the red filter formation region is removed by photolithography. Thereafter, the dyed substrate is dyed with a red dye and subjected to a fixing treatment to form a red filter R. Next, a green filter G and a blue filter B are sequentially formed by performing a similar process.

Although the present invention has been specifically described based on the embodiments, the present invention is not limited to the above-described embodiments, and it is needless to say that various modifications can be made without departing from the scope of the invention. It is. For example, the present invention is applicable to an active matrix type liquid crystal display device of a vertical electric field type or a horizontal electric field type, a simple matrix type liquid crystal display device, or a COG (chip-on-glass) type liquid crystal display device. Needless to say. Further, the present invention is not limited to a display unit such as a personal computer, and can be applied to a display unit of various information processing devices such as a camera. In the embodiments shown in FIGS. 1 and 2, the light storage layer 1 is provided on the black matrix 5, but the light storage layer 1 may be provided in a region other than the pixel region which does not hinder display. Alternatively, it may be provided in at least one region of a video signal line and a scanning signal line. In addition, the present invention can be applied to a case where the black matrix in the present invention is formed of a metal film such as Cr or Al, or a case where the black matrix is formed of an organic resin film colored black or the like.

[0049]

As described above, according to the present invention,
In a dark place, it is possible to realize a reflective liquid crystal display device that can display a screen display without consuming power for a light source such as a front light.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a main part of a reflection type liquid crystal display panel according to an embodiment of the present invention, in which (a) shows a case where external light is present, and (b) shows a case where there is no external light. .

FIG. 2 is a schematic cross-sectional view of a main part, showing more specifically the reflective liquid crystal display panel of FIG.

3 (a) to 3 (f) are schematic sectional views showing steps of a method for manufacturing one substrate for manufacturing the liquid crystal display panel shown in FIGS. 1 and 2. FIG.

FIG. 4 is a main part plan view showing one pixel of a reflection type color liquid crystal display panel of an active matrix vertical electric field type to which the present invention is applied and the periphery thereof.

5 is a cross-sectional view showing one pixel and its surroundings taken along a line 5-5 in FIG. 4;

FIG. 6 is a schematic cross-sectional view of a main part of an example of a conventional reflective liquid crystal display panel.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light storage layer, 2 ... Polarizing plate, 3 ... Transparent glass substrate, 4 ... Black matrix, 5 ... Color filter, 6 ... Liquid crystal layer,
7: reflection layer, 8a, 8b, 8c: light path, 10: liquid crystal display panel, 5R, 5G, 5B: red, green, blue color filter, 11: protective film of color filter, 12: common transparent pixel electrode.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuji Mori 3300 Hayano, Mobara-shi, Chiba F-term in the Electronic Devices Division, Hitachi, Ltd. (Reference) 2H091 FA02Y FA08X FA14Z FA35Y FA43Y FA50Y FB06 FC02 FC12 FD04 FD06 GA13

Claims (3)

[Claims] 1. A liquid crystal display device according to claim 1, wherein a light storage layer for storing light is provided in a region other than the pixel region. 2. A liquid crystal display device comprising: two substrates superposed at a predetermined interval; a liquid crystal layer sealed between the two substrates; a display electrode provided on at least one of the opposing surfaces of the two substrates; A polarizing plate provided on the outer surface side of the first substrate on the display screen side;
In a liquid crystal display device provided with a reflection type liquid crystal display panel comprising a reflection layer provided on the opposite surface side of the substrate, a light storage layer for storing light is provided in a region other than the pixel region. Liquid crystal display device. 3. A light emitting device according to claim 2, wherein a black matrix is provided on a surface of said first substrate facing said liquid crystal layer, and said light storage layer is provided on a surface of said black matrix on a side of said liquid crystal layer. The liquid crystal display device as described in the above.