JP2000171805A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the breakdown of circuits, etc., which occur in the concentration of local stresses to columnar spacers by contact of the columnar spacers with a counter substrate. SOLUTION: This liquid crystal display device has a first substrate SUB1 which has many pixel electrodes AL-P formed in a matrix form, a second substrate SUB2 which is disposed to face apart a prescribed spacing to this first substrate SUB1 and has transparent electrodes ITO-C, a liquid crystal layer SL which consists of a liquid crystal composition encapsulated into the opposite spacing between the first substrate and the second substrate, alignment layers OR11, OR12 which are deposited on the respective surfaces of the first substrate and the second substrate in contact with the liquid crystal layer and control the alignment of the liquid crystal composition and the plural columnar spacers SPC-P which are formed to project so as to hold the opposite spacing with the second substrate in the display region of the first substrate at a prescribed value. The area at the front ends of the columnar spacers in contact with the inside surface of the second substrate is made smaller than the area of the base parts connected to the inside surface of the first substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device having a columnar spacer for keeping a gap between liquid crystal layers at a predetermined value while avoiding light leakage.

[0002]

2. Description of the Related Art A display device using a liquid crystal panel has been widely used as a projection display device, a notebook computer, or a display device capable of high-definition and color display for a display monitor.

A display device using a liquid crystal panel (a liquid crystal display device) includes a simple matrix type using a liquid crystal panel in which a liquid crystal layer is sandwiched between a pair of substrates on which parallel electrodes formed so as to intersect with each other are formed. An active matrix type liquid crystal display device using a liquid crystal display element (hereinafter, also referred to as a liquid crystal panel) having a switching element for selecting a pixel in one of a pair of substrates is known.

An active matrix type liquid crystal display device is
A so-called vertical electric field type liquid crystal display device (generally, a TN type active matrix type) using a liquid crystal panel in which an electrode group for pixel selection is formed on a pair of upper and lower substrates as represented by a twisted nematic (TN) type. A liquid crystal panel in which an electrode group for pixel selection is formed only on one of a pair of upper and lower substrates,
There is a so-called in-plane switching mode liquid crystal display device (generally referred to as an IPS mode liquid crystal display device).

[0005] A projection display device is known as one of applied devices of the liquid crystal display device. A projection type liquid crystal display device using a liquid crystal panel projects an image generated on a small liquid crystal panel onto a screen by an enlargement optical system to obtain a large screen display. This type of projection type liquid crystal display device includes a transmission type and a reflection type, and the transmission type is configured such that two insulating substrates forming a liquid crystal panel are both formed of a transparent substrate such as a glass plate,
Illumination light is emitted from the back, and the transmitted modulated light is enlarged and projected by a projection optical system. On the other hand, the reflection type uses a projection optical system to enlarge and project reflected light modulated by an image generated by irradiating illumination light from the front side with one insulating substrate as a reflection plate.

[0006] Note that a notebook computer or a direct-view type liquid crystal display device for a display monitor is also known in which one of the insulating substrates constituting the liquid crystal panel is used as a reflection plate to utilize light from the display surface side. Have been.

In a liquid crystal panel constituting a liquid crystal display device, a liquid crystal layer made of a liquid crystal composition is generally sandwiched in a gap between two insulating substrates such as glass substrates, and the periphery thereof is sealed with a sealant. . The gap between the two insulating substrates is an extremely narrow gap (referred to as a cell gap) of, for example, about 4 to 7 μm. One method for maintaining the cell gap is to randomly disperse beads having a substantially uniform diameter. Let me.

To reliably control the cell gap, it is better to increase the amount of dispersion of beads. However, since the dispersion of beads is random and non-uniform, light leakage occurs when locally densely formed portions are formed. In general, the dispersion amount is set to about 150 particles / mm ² because there is a side effect such as a decrease in contrast due to disordered liquid crystal alignment around the beads.

Organic beads or quartz can be used as a material for the beads. In the case of quartz beads, a protective film, an electrode, or a switching element such as a TFT formed on an insulating substrate in a pressing step at the time of setting a cell gap is destroyed. There is a problem that bubbles occur due to a change in temperature due to a difference in thermal expansion coefficient from the liquid crystal composition. Therefore, generally, an organic polymer is used.

In a direct-view type liquid crystal panel, stress is easily applied to an insulating substrate, so that dispersed beads may move. For this reason, it is desirable that the liquid crystal layer be kept under a negative pressure with respect to the atmosphere. However, it is difficult to keep the completed liquid crystal panel constantly under a negative pressure in terms of the manufacturing process.

On the other hand, in a small liquid crystal display device used for a projection type display device, when beads are dispersed between insulating substrates of the liquid crystal panel, beads existing in a display area are enlarged and projected on a screen, and display quality is improved. There is a problem that it deteriorates. Therefore, a beadless system in which beads or fibers are inserted only around the display area of the liquid crystal panel and the cell gap is held only around the periphery is also known. However, in the beadless method, it is difficult to maintain the cell gap in the display area at a predetermined value, which causes a decrease in yield and a deterioration in image quality.

Further, in recent years, the demand for higher display speeds has made it necessary to further narrow the cell gap, that is, to narrow the cell gap, and it is required that the precision of the gap control be 0.1 μm or less. Along with the narrowing of the gap, it is necessary to further improve the processing accuracy of the beads, but this is also extremely difficult, and it is particularly difficult in the reflection type since the cell gap is half that of the transmission type.

In order to solve such a cell gap problem, a columnar spacer (hereinafter, referred to as a columnar spacer) which bridges between two insulating substrates by a photolithography technique is provided on the insulating substrate. It is proposed to be formed at a specific location (a location that does not affect display, such as between pixels or immediately below a black matrix).

By using this columnar spacer, local deviation or movement of the beads caused when the beads are dispersed is eliminated. Furthermore, since the processing accuracy of the photolithography technique is orders of magnitude better than the processing accuracy of beads, the height of the columnar spacer is determined only by the film thickness when the columnar spacer material (photoresist) is applied. The accuracy can be expected to improve dramatically.

[0015]

However, in a liquid crystal panel using such a columnar spacer, one substrate (drive circuit substrate: FT in a thin film transistor TFT system) is used.
The stress generated due to the difference in thermal expansion between the F substrate and the other substrate (counter substrate: a color filter substrate in the case of a color), and local to the column spacer caused by irregularities on the inner surface of the counter substrate that comes into contact with the column spacer. Stress concentration occurs, and the position and displacement of the columnar spacers or bites into the electrodes, wirings, or drive circuits occur, which causes a problem of display failure of the liquid crystal panel.

An object of the present invention is to solve the above-mentioned problems of the prior art and to improve the shape of the columnar spacer to eliminate the concentration of local stress on the columnar spacer due to the contact with the counter substrate. It is to provide a device.

[0017]

In order to achieve the above object, the present invention reduces the area of the tip of a columnar spacer formed on the inner surface of one insulating substrate of a liquid crystal panel constituting a liquid crystal display device. The contact area with the other substrate in contact with the spacer was reduced.

That is, the columnar spacer according to the present invention comprises:
It is formed by photolithography on one substrate, for example, a driving substrate. This columnar spacer has a somewhat large area in the cross section on the driving substrate side due to adhesion to the driving substrate and stress dispersibility, and the area of the tip of the other substrate, for example, the opposing substrate side is the gap of the liquid crystal layer. Is reduced as much as possible within a range that can be maintained.

The shape of the tip of the columnar spacer is preferably a dome shape with a rounded surface. The shape of the tip surface may be a hemisphere, an elliptical sphere, or any other curved surface, regardless of the overall shape of the columnar spacer, or, if the columnar spacer is prismatic, have a rounded upper surface. May be.

A typical configuration of the present invention is described as follows. That is, (1) a first substrate having a large number of pixel electrodes formed in a matrix, a second substrate having a transparent electrode opposed to the first substrate with a predetermined gap, and a first substrate Layer composed of a liquid crystal composition sealed in a gap between the first substrate and the second substrate, and an alignment film for controlling the alignment of the liquid crystal composition formed on each surface of the first substrate and the second substrate in contact with the liquid crystal layer And a plurality of columnar spacers formed in the display area of the first substrate so as to protrude so as to maintain a facing gap with the second substrate at a predetermined value, and an inner surface of the columnar spacer of the second substrate. The area of the contacting tip is smaller than the area of the base connected to the inner surface of the first substrate.

According to this structure, the cell gap in the display area can be made uniform, and the local stress caused by the contact pressure with the columnar spacer due to the unevenness of the inner surface of the substrate can be reduced. Therefore, destruction of the electrodes, thin film transistors, and other functional structures in the display region is avoided, and the manufacturing yield and reliability are improved.

(2) The columnar spacer of (1) was formed of a resist material formed by photolithography.

According to the columnar spacer formed in this way, it is possible to obtain an accurate cell gap having the same shape and height.

It should be noted that the present invention is not limited to the above configuration, and various changes can be made without departing from the technical idea of the present invention.

[0025]

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

FIG. 1 is a schematic sectional view of a liquid crystal panel for explaining a first embodiment of a liquid crystal display device according to the present invention. This liquid crystal panel is a reflection type liquid crystal panel used for a liquid crystal projection type liquid crystal display device, and DSUB is a lower substrate (drive substrate) composed of a single crystal silicon substrate SUB1 as a first substrate, US
UB is an upper substrate (counter substrate) composed of a transparent glass substrate SUB2 as a second substrate, LC is a liquid crystal layer made of a liquid crystal composition, ORI1 is a lower alignment film, ORI2 is an upper alignment film, and AL- P is a pixel electrode, TM is a terminal, PSV1
Is a protective film, SPC-P is a columnar spacer, SPC-S is a strip spacer, SL is a sealant, and SHF is a light shielding film.

This liquid crystal panel is assumed to be of an active matrix type composed of thin film transistors TFT, and only the pixel electrodes AL-P are shown on the drive substrate DSUB, but the thin film transistors TFT and TFT are used as switching elements for pixel selection. A storage capacitor and the like are formed.

A counter substrate USUB on which a counter electrode ITO-C and an alignment film ORI2 are formed, a driving substrate D on which a pixel electrode AL-P, a protective film PSV1, and an alignment film ORI1 are formed.
A liquid crystal layer LC made of a liquid crystal composition is sandwiched between the SUBs. The pixel electrode AL-P is an electrode and has a reflection function, and emits light incident from the counter substrate USUB again from the counter substrate USUB.

The driving substrate DSUB has a columnar spacer SPC-on the protective film PSV1 at a position avoiding the pixel electrode.
P is formed, and band-shaped spacers SPC-S are formed on the periphery of the attachment of the two substrates, that is, on the outer periphery of the display area where the pixel electrodes AL-P and the like are formed. Strip spacer SPC
The width dimension of -S is larger than the diameter dimension of the columnar spacer SPC-P, and the pressing force when two substrates are bonded and pressed to each other to accurately set the cell gap in the peripheral cell gap. The cell gap of the display area is controlled to a predetermined value in cooperation with P.

That is, when the two substrates are overlapped and pressed, the columnar spacer SPC-P and the band-shaped spacer SPC
The gap between the substrates, that is, the cell gap of the liquid crystal layer is accurately controlled by the height of -S. A method of sealing the liquid crystal layer in the display region is to drip the liquid crystal composition in the display region before the two substrates are overlapped, and to overflow and press the surplus liquid crystal composition when bonding with the sealing agent SL, An opening is formed in a part of the band-shaped spacer SPC-S, the two substrates are overlapped, a sealing agent SL containing no filler is applied along the outer edge of the band-shaped spacer SPC-S, and semi-cured by ultraviolet irradiation or the like. After that, the liquid crystal composition is injected from the opening in a state where the atmosphere is kept under a negative pressure, and then the sealing agent SL is completely cured by pressing and heating to set the cell gap.

Although not shown, in the case of a projection type liquid crystal display device, a terminal of a flexible printed board for connecting a signal for driving a switching element is connected to a terminal portion TM.

FIG. 2 is a schematic sectional view of a liquid crystal panel for explaining a second embodiment of the liquid crystal display device according to the present invention. In this liquid crystal panel, a color filter FIL of three colors partitioned by a light shielding film (black matrix) BM is formed on a counter substrate USUB as a second substrate, and a common electrode ITO-C is formed thereon.
It is the same as the first embodiment except that an orientation film ORI2 is formed.

FIG. 3 is a plan view for explaining the arrangement of the column spacers of the liquid crystal panel shown in FIG. 1 or FIG. The arrangement of the columnar spacers is indicated by the positional relationship with the pixel electrodes.

Columnar spacer SPC formed in display area
−P is provided at a place where the pixel electrode AL-P crosses. In this embodiment, the provision of the columnar spacer SPC-P in the space between the pixel electrodes does not significantly reduce the aperture ratio. The columnar spacers SPC-P may not be provided between all the pixel electrodes. However, by providing one columnar spacer SPC-P in the space between all the pixel electrodes, the number of spacers to be installed can be reduced as compared with the case where beads are used. Is increased by orders of magnitude, a powerful cell gap control function is exhibited, and no displacement between the two substrates occurs.

A strip spacer SPC-S is formed on a light-shielding film SHF formed of the same layer as the pixel electrodes on the outer periphery of the display area where the pixel electrodes are arranged. The band-shaped spacer SPC-S is formed so as to surround the outer periphery of the display area, and its width is larger than the diameter of the columnar spacer SPC-P. The band-shaped spacer SPC-S has a function of sealing the liquid crystal layer LC, and the sealant SL, which is conventionally arranged so as to be in contact with the liquid crystal layer, is applied to the outer edge of the band-shaped spacer SPC-S ( 1 and 2).

The columnar spacer SPC-P and the band spacer S
PC-S is formed simultaneously by photolithography technique. Materials for these spacers include JSR Corporation
Amplified Negative Type Resist "BPR-113"
(Trade name) was used. This resist material is made of a material very similar to the bead material used in conventional liquid crystal panels, does not dissolve or swell in the liquid crystal composition after thermosetting, and has good compatibility with the liquid crystal composition. Good workability.

FIG. 4 is a photomicrograph of a section of a columnar spacer according to this embodiment. As shown in the figure, the columnar spacer SPC-P is formed on the circuit CCT of the driving substrate (first substrate) SUB1, and the area of the base is somewhat large due to the adhesion to the driving substrate and the stress dispersion. The area of the front end portion on the side of the opposing substrate, which is the other substrate, is a rounded dome shape as small as possible within a range that can maintain the gap of the liquid crystal layer.

The column spacer SPC-P (and the band spacer SPC-S) is, for example, the "BPR-113" which is a material of the column spacer and the band spacer.
Is applied on the protective film PSV1 (see FIG. 1) of the drive substrate DSUB on which the pixel electrodes AL-P are formed by spin coating, exposed by i-line, and developed.

FIG. 5 is a cross-sectional view of the second embodiment using the columnar spacer of this embodiment.
It is a schematic diagram explaining the state at the time of pressing and bonding two substrates.

This figure shows a case where the opposing substrate has a convex portion on the inner surface. As shown in FIG.
In the case where there is a common electrode or an alignment film formed on the inner surface of B2, or a projection P caused by a color filter, the columnar spacer is a simple columnar or prismatic having the same area at the base and the tip. There is a possibility that the columnar spacer may be separated from the formation position by the pressing force of the two substrates indicated by the arrows, or the drive circuit and the like formed thereunder may be destroyed. However, in this embodiment, the columnar spacer SP
Since the area of the tip of CP is formed small, the columnar spacer SPC-P hitting the convex part P is subjected to a stress due to the crimping force due to the collapse of the tip as shown in FIG. Is alleviated.

Even when stress is generated between the columnar spacer and the opposing substrate due to a difference in the coefficient of thermal expansion between the driving substrate and the opposing substrate, the gap (cell gap) of the liquid crystal layer is small due to the small contact area between them. The contact part is easily displaced while maintaining the condition.

Therefore, separation from the formation position of the columnar spacer or destruction of the drive circuit and the like formed thereunder can be avoided.

Then, the strip spacer SPC- of the drive substrate DSUB on which the column spacer and the strip spacer are formed.
The liquid crystal composition is injected into the inside surrounded by S. Note that FIG.
Closed loop band spacer SPC-
In the case of S, the liquid crystal composition is dropped. The common substrate USUB is placed on the drive substrate DSUB so as not to come into contact with the drive substrate DSUB and deaeration processing is performed. After degassing, both substrates are pressed by a press and brought into close contact. At this time, the excess liquid crystal composition protrudes from the strip spacer SPC-S. The protruding liquid crystal composition is washed away, and a sealant SL containing no filler is applied between the outer edge of the strip spacer SPC-S and the two substrates to be cured.

As described above, according to this embodiment, the column spacer SPC-P and the strip spacer SPC-S make the cell gap between the display region and the seal portion equal, thereby avoiding a circuit breakdown or the like due to the column spacer SPS-P. The occurrence of display unevenness due to the cell gap difference is prevented.

Further, as in this embodiment, the sealing agent SL
The liquid crystal composition constituting the liquid crystal layer LC does not come in contact with the sealant by disposing the band-shaped spacer SPC-S inside the
The contamination of the liquid crystal composition by the uncured sealant is prevented, and it is not necessary to include a filler in the sealant. The thin film is not destroyed.

FIG. 6 is a plan view for explaining another configuration example of the liquid crystal panel of the liquid crystal display device according to the present invention. In this configuration example, a strip spacer SPC-
A gap is provided in a part of S, which is used as a liquid crystal injection port INJ. The other configuration is the same as the configuration shown in FIG. 3 and thus the description is omitted. Hereinafter, a method of manufacturing the liquid crystal panel of this embodiment will be described.

The driving substrate DSUB is a belt-shaped spacer SPC
Except that the liquid crystal injection port INJ is provided in -S, it is formed in the same manner as in the first embodiment. The opposing substrate USUB is bonded to the driving substrate DSUB, and the two are brought into close contact with each other by pressing with a press. In this state, the atmosphere is decompressed and degassed, and the liquid crystal composition is injected from the liquid crystal inlet INJ.

Thereafter, a sealant is applied to the outer edge of the strip spacer SPC-S including the liquid crystal inlet INJ and is cured. The operation of the columnar spacer SPS-P at this time is shown in FIG.
As described in the above.

Further, before applying the sealant to the outer edge of the strip spacer SPC-S, the same type of sealant may be applied to the liquid crystal inlet INJ and sealed. Although this liquid crystal inlet INJ is shown as one, two or more liquid crystal inlets I
NJs may be provided side by side. According to this embodiment, the same effects as those of the first embodiment can be obtained.

In each of the above-described configuration examples, the driving substrate D
Although the reflection type using a single crystal silicon substrate for the SUB has been described, the same configuration can be applied to a transmission type in which both substrates are glass substrates or a direct-view type liquid crystal display device having a large display area.

Next, a case in which the present invention is embodied will be described. FIG. 7 is an explanatory diagram of the overall configuration of a projection type liquid crystal display device embodying the liquid crystal display device according to the present invention,
(A) is a partially broken plan view, (b) is AA of (a).
It is a cross section along the line.

As shown in FIG. 7, this projection type liquid crystal display device has a columnar spacer SPC-P on a second substrate DSUB.
And a first substrate US having a band-shaped spacer SPC-S
The liquid crystal layer LC is sandwiched between the UB and the second substrate DSUB, and the columnar spacer SPC-P and the band-shaped spacer SPC are sandwiched.
-S controls the required cell gap and sets the band-shaped spacer SP
A reflective liquid crystal panel formed by applying and curing a sealant SL on the outer edge of the CS and adhering the two substrates to each other is housed in a cavity of a package PCG suitable for a molded product of a resin material. One end of a flexible printed circuit board FPC for supplying a signal and power to the edge is connected, and the cavity is closed by covering with a surface glass WG.

On the back of the package PCG, a metal heat radiating plate PPB is installed with its periphery buried in the lower four sides of the package main body PCG, and the liquid crystal panel has relatively elasticity with the heat radiating plate PPB. It is stored via the heat dissipation sheet DPH. Therefore, the rear surface of the liquid crystal panel is in close contact with the heat radiating plate PPB by the heat radiating sheet DPH, and has a structure in which a sufficient heat radiating effect can be obtained.

The liquid crystal panel housed inside the cavity of the package PCG is fixed to the step formed on the inner periphery of the bottom of the package PCG by the adhesive ADH on the back side of the first substrate USUB. With adhesive PCG and flexible printed circuit board FP
It is fixed to a space plate SPB for fixing C. The space plate SPB is a flexible printed circuit board FP
C is fixed using an adhesive (not shown).

FIG. 8 is a schematic diagram for explaining a configuration example of a projection type liquid crystal display device using the liquid crystal display device described with reference to FIG. 7, and a liquid crystal display device (liquid crystal module) MOD is provided in a casing CAS. , Illumination light source LSS, illumination lens system L
NS, a first polarizing plate POL1, a reflecting mirror MIL, an imaging lens system FLN, a second polarizing plate POL2, an optical diaphragm ILS,
And the projection optical system PLN.

The irradiation light from the light source device LSS is incident on the surface of the liquid crystal panel PNL constituting the liquid crystal display device MOD by the illumination lens system LNS, the first polarizing plate POL1, and the reflecting mirror MIL. The light incident on the liquid crystal panel PNL is modulated according to the image signal by the pixel electrode AL-P of the liquid crystal panel PNL, and the reflected light is reflected by the imaging lens system FLN, the second polarizing plate Pd2, the optical diaphragm ILS, and the projection optics. The image is enlarged and projected on the screen SCN via the system PLN.

Next, an example in which the present invention is applied to a direct-view type liquid crystal display device will be described for an active matrix type liquid crystal display device.

FIG. 9 is a plan view of a liquid crystal panel constituting an active matrix type liquid crystal display device. The upper and lower transparent glass substrates SUB2 (color filter substrate) and SUB1 (active matrix substrate) which are first and second insulating substrates. ), And FIG. 10 is an enlarged plan view near the seal portion SL corresponding to the upper left corner of the liquid crystal panel shown in FIG.

FIGS. 11A and 11B are cross-sectional views of main parts of the liquid crystal panel. FIG. 11A is a cross-sectional view taken along line 19a-19a in FIG. 9, FIG. 11B is a cross-sectional view of a TFT portion, and FIG. FIG. 2 is a cross-sectional view showing the vicinity of an external connection terminal DTM to which a signal line driving circuit is to be connected.

In the manufacture of this liquid crystal panel, if the size is small, a plurality of glass substrates are simultaneously processed on a single glass substrate and then separated in order to improve the throughput. A glass substrate of a standardized size is also processed for a product type, and then reduced to a size suitable for each product type. In each case, the glass substrate is cut after passing through one process.

9 and 11 show the upper and lower glass substrates SUB2 and SUB1 after cutting, and FIG. 10 shows the state before cutting. LN indicates the edge of the cutting line of the glass substrate, and CT1 and CT2 indicate the edges. The positions where the glass substrates SUB1 and SUB2 are to be cut are shown.

In any case, in the completed state, the portions (the upper and lower sides and the left side in the figure) where the external connection terminal groups Tg and Td (subscripts are omitted) have a size of the upper glass substrate SUB2 such that they are exposed. It is limited inside the lower glass substrate SUB1.

The external connection terminal groups Tg and Td are a scanning circuit connection terminal GTM and a video signal circuit connection terminal DTM, respectively.
And a plurality of these lead-out wiring portions are collectively named for a unit of a tape carrier package on which a drive circuit chip is mounted. The lead wiring from the matrix part of each group to the external connection terminal part is inclined as approaching both ends. This is for adjusting the terminals DTM and GTM of the liquid crystal panel PNL to the arrangement pitch of the tape carrier package and the connection terminal pitch of each tape carrier package.

The columnar spacer SPC-P is provided in the display area AR between the transparent glass substrates SUB1 and SUB2, and the liquid crystal LC is sealed along the edge of the sealing portion except for the liquid crystal filling opening INJ. A strip spacer SPC-S is formed. The sealing agent SL is applied to the outer edge of the strip spacer SPC-S. This sealant is made of, for example, an epoxy resin. The columnar spacer SPC-
P is not shown in FIG. 11 because it is formed at the boundary between pixels.

The common transparent pixel electrode ITO2 on the upper transparent glass substrate SUB2 side is connected to the lead-out wiring IN formed on the lower transparent glass substrate SUB1 side by a silver paste material AGP at at least one position, here, at four corners of the liquid crystal panel.
Connected to T. The lead wiring INT is formed in the same manufacturing process as the gate terminal GTM and the drain terminal DTM.

The layers of the alignment films ORI1 and ORI2, the transparent pixel electrode ITO1, and the common transparent pixel electrode ITO2 are formed inside the strip spacer SPC-S.
Lower transparent glass substrate SUB1, upper transparent glass substrate SU
Polarizing plates POL1 and POL2 are formed on the outer surface of B2.

The liquid crystal LC has a display area AR partitioned by a strip spacer SPC-S between a lower alignment film ORI1 and an upper alignment film ORI2 for setting the direction of liquid crystal molecules of the liquid crystal composition.
It is enclosed in. The lower alignment film ORI1 is formed above the protective film PSV1 on the lower transparent glass substrate SUB1 side.

In the liquid crystal panel PNL, various layers are separately stacked on the transparent glass substrate SUB1 side and the upper transparent glass substrate SUB2 side, and the lower transparent glass substrate SUB1 and the upper transparent glass substrate SUB2 are overlapped to form a strip spacer SPC-. The liquid crystal is injected from the opening INJ (liquid crystal injection port) of the S, then sealed with the sealant SL, and the upper and lower transparent glass substrates are cut and assembled.

The thin film transistor TFT shown in FIG.
Operates such that when a positive bias is applied to the gate electrode GT, the channel resistance between the source and the drain decreases, and when the bias is reduced to zero, the channel resistance increases.

The thin film transistor TFT of each pixel is divided into two (a plurality) in the pixel. In FIG. 11, only one is shown. Two thin film transistors TFT
Are substantially the same size (channel length and channel width are the same). Each of the divided thin film transistors TFT includes a gate electrode GT, a gate insulating film GI, and an i-type semiconductor layer AS made of i-type (intrinsic, intrinsic, not doped with a conductivity type determining impurity) amorphous silicon (Si). , A pair of source electrode SD1 and drain electrode SD2. The source,
It should be understood that the drain is originally determined by the bias polarity between them, and in the circuit of this liquid crystal display device, the polarity is inverted during operation, so that the source and drain are switched during operation. However, in the following description, for convenience, one is fixed as a source and the other is fixed as a drain.

The gate electrode GT is a thin film transistor TFT
And each gate electrode GT of the thin film transistor TFT is formed continuously. Here, the gate electrode GT is
It is formed of a single-layer second conductive film g2. Second conductive film g
2 is, for example, aluminum (A) formed by sputtering.
l) A film is formed with a thickness of about 1000 to 5500 °. Further, an anodic oxide film AOF of aluminum is provided on the gate electrode GT.

This gate electrode GT is formed larger than it so as to completely cover the i-type semiconductor layer AS (as viewed from below). Therefore, when a backlight BL such as a fluorescent tube is attached below the lower transparent glass substrate SUB1,
The gate electrode GT made of the opaque aluminum film becomes a shadow, and the light from the backlight does not shine on the i-type semiconductor layer AS. Note that the original size of the gate electrode GT is at least necessary to extend between the source electrode SD1 and the drain electrode SD2 (the gate electrode GT and the source electrode SD1, the drain electrode SD2).
(Including a margin for positioning), and the depth length that determines the channel width W is the ratio of the distance (channel length) L between the source electrode SD1 and the drain electrode SD2, that is, the mutual conductance gm. Factor W /
It is determined by what L is. The size of the gate electrode GT in this liquid crystal display device is, of course, made larger than the original size described above.

The scanning signal line is composed of the second conductive film g2. The second conductive film g2 of this scanning signal line is connected to the gate electrode G
It is formed in the same manufacturing process as the second conductive film g2 of T, and is integrally formed. Also, an anodic oxide film AOF of aluminum Al is provided on the scanning signal lines.

The insulating film GI is used as each gate insulating film of the thin film transistor TFT, and the gate electrode GT
And on the scanning signal line. Insulating film GI
Is formed using a silicon nitride film formed by, for example, plasma CVD, to a thickness of 1200 to 2700 ° (in this liquid crystal display device, a thickness of about 2000 °). As shown in FIG. 9, the gate insulating film GI is formed so as to surround the entire matrix portion AR, and the peripheral portion is provided with the external connection terminal DT.
M and GTM have been removed to expose them.

The i-type semiconductor layer AS is used as a channel formation region of each of two thin film transistors TFT. The i-type semiconductor layer AS is formed of an amorphous silicon film or a polycrystalline silicon film and has a thickness of 200 to 220 ° (about 200 ° in this liquid crystal display device).

The i-type semiconductor layer AS is formed by the same plasma CVD method by changing the composition of the supply gas and forming an insulating film GI used as a gate insulating film made of Si ₂ N _4.
It is formed by an apparatus and without being exposed to the outside from the plasma CVD apparatus.

Similarly, the N (+) type semiconductor layer d0 doped with 2.5% of phosphorus (P) for ohmic contact is continuously formed to a thickness of 200 to 500 ° (in this liquid crystal display device, about 300 °). (Film thickness). Thereafter, the lower transparent glass substrate SUB1 is taken out of the CVD apparatus, and the N (+)-type semiconductor layer d0 and the i-type semiconductor layer AS are patterned into independent islands by a photographic processing technique.

The i-type semiconductor layer AS is also provided between both intersections (crossover portions) of the scanning signal lines and the video signal lines. The i-type semiconductor layer AS at the intersection reduces a short circuit between the scanning signal line and the video signal line at the intersection.

The transparent pixel electrode ITO1 (corresponding to AL-P in FIG. 1) forms one of the pixel electrodes of the liquid crystal panel. The transparent pixel electrode ITO1 is connected to each source electrode SD1 of two thin film transistors TFT. Therefore, even if a defect occurs in one of the two thin film transistors TFT, if the defect causes a side effect, an appropriate portion is cut by a laser beam or the like, otherwise, the other thin film transistor operates normally. You can leave it. It is rare that defects occur in two thin film transistors TFT at the same time, and the occurrence probability of point defects and line defects can be extremely reduced by such a redundant system.

The transparent pixel electrode ITO1 is composed of the first conductive film d1. This first conductive film d1 is a transparent conductive film (Indium-Tin) formed by sputtering.
-Oxide ITO: Nesa film)
A film thickness of 2000 ° ((1400 in this liquid crystal display device)
(Å film thickness).

The source electrode SD1 and the drain electrode SD2 of each of the two thin film transistors TFT are provided separately on the i-type semiconductor layer AS.

Each of the source electrode SD1 and the drain electrode SD2 is formed by sequentially stacking a second conductive film d2 and a third conductive film d3 from the lower side in contact with the N (+) type semiconductor layer d0. Second conductive film d of source electrode SD1
The second and third conductive films d3 are the second conductive films d3.
The conductive film d2 and the third conductive film d3 are formed in the same manufacturing process.

The second conductive film d2 is formed by using a chromium (Cr) film formed by sputtering and having a thickness of 500 to 1000 （(about 600 液晶 in this liquid crystal display device). The Cr film is aluminum A of a third conductive film d3 described later.
A so-called barrier layer for preventing l from diffusing into the N (+) type semiconductor layer d0 is formed. Cr as the second conductive film d2
In addition to the film, a film of a high melting point metal (Mo, Ti, Ta, W, etc.), a high melting point metal silicide (MoSi ₂ , TiSi ₂ ,
TaSi ₂ , WSi _2, etc.) can also be used.

The third conductive film d3 is formed by sputtering aluminum Al to a thickness of 3000 to 5000 ° (about 4000 ° in this liquid crystal panel). The aluminum Al film has a smaller stress than the chromium Cr film and can be formed in a thick film.
1. The configuration is such that the resistance values of the drain electrode SD2 and the video signal line DL are reduced. As the third conductive film d3, an aluminum film containing silicon or copper (Cu) as an additive in addition to normal aluminum can be used.

After patterning the second conductive film d2 and the third conductive film d3 with the same mask pattern, using the same mask or using the second conductive film d2 and the third conductive film d3 as a mask, an N (+) type The semiconductor layer d0 is removed. That is, in the N (+)-type semiconductor layer d0 remaining on the i-type semiconductor layer AS, portions other than the second conductive film d2 and the third conductive film d3 are removed by self-alignment. At this time, since the N (+)-type semiconductor layer d0 is etched so as to remove all of its thickness, the i-type semiconductor layer AS is also slightly etched at its surface. What is necessary is just to control by processing time.

The source electrode SD1 is a transparent pixel electrode ITO1.
It is connected to the. The source electrode SD1 is formed by a step of the i-type semiconductor layer AS (the thickness of the second conductive film d2, the anodic oxide film AOF).
, The thickness of the i-type semiconductor layer AS, and the thickness of the N (+)-type semiconductor layer d0). Specifically, the source electrode SD1 is i
Conductive film d formed along the step of the semiconductor layer AS
2 and a third conductive film d3 formed on the second conductive film d2. Since the third conductive film d3 of the source electrode SD1 cannot increase the thickness of the Cr film of the second conductive film d2 due to an increase in stress and cannot climb over the step of the i-type semiconductor layer AS, the third conductive film d3 needs to get over the i-type semiconductor layer AS. It is configured. That is, the step coverage is improved by increasing the thickness of the third conductive film d3. Third conductive film d3
Can be formed thick, which greatly contributes to a reduction in the resistance value of the source electrode SD1 (the same applies to the drain electrode SD2 and the video signal line DL).

A protective film PSV1 is provided on the thin film transistor TFT and the transparent pixel electrode ITO1. The protective film PSV1 is formed mainly for protecting the thin film transistor TFT from moisture, and a film having high transparency and good moisture resistance is used. The protective film PSV1 is formed of, for example, a silicon oxide film or a silicon nitride film formed by a plasma CVD device, and has a thickness of about 1 μm.

As shown in FIG. 10, the protective film PSV1 is formed so as to surround the entire matrix portion AR, the peripheral portion is removed so as to expose the external connection terminals DTM and GTM, and the upper transparent glass substrate is formed. Common electrode C of SUB2
OM (corresponding to the transparent electrode ITO-C in FIG. 1) is connected to a lead-out wiring INT for connecting an external connection terminal of the lower transparent glass substrate SUB1.
The part connected with silver paste AGP is also removed.
Regarding the thickness relationship between the protective film PSV1 and the gate insulating film GI, the former is made thicker in consideration of the protective effect, and the latter is made thinner in consideration of the transconductance gm of the transistor.
Therefore, as shown in FIG.
The SV1 is formed larger than the gate insulating film GI so as to protect the peripheral portion as much as possible.

On the side of the upper transparent glass substrate SUB2, an i-type semiconductor layer A in which external light is used as a channel formation region is provided.
The light shielding film BM is provided so as not to enter S.

The light-shielding film BM has a high light-shielding property against light,
For example, it is formed of an aluminum film, a chromium film, or the like. In this liquid crystal display device, the chromium film is formed by sputtering at 130
It is formed to a thickness of about 0 °. This light-shielding film is shown in FIG.
Is different from the light shielding film SHF.

Therefore, the i of the thin film transistor TFT
The type semiconductor layer AS is sandwiched between the upper and lower light shielding films BM and the large gate electrode GT, and the portion is not exposed to external natural light or backlight. As shown by hatching in FIG. 11, the light-shielding film BM is formed around the pixel, that is, the light-shielding film BM is formed in a lattice shape (a so-called black matrix), and an effective display area of one pixel is partitioned by the lattice. ing. With this light shielding film BM,
The outline of each pixel is clear, and the contrast is improved. In other words, the light-shielding film BM shields the i-type semiconductor layer AS from light and transmits color filters FIL (R), FIL (G), FI
It has two functions: a black matrix for improving contrast by partitioning between L (B).

Also, since the portion of the transparent pixel electrode ITO1 facing the edge on the root side in the rubbing direction is shielded from light by the light-shielding film BM, even if a domain is generated in the above-mentioned portion, the domain is not visible. The characteristics do not deteriorate.

Note that the backlight can be attached to the upper transparent glass substrate SUB2 side, and the lower transparent glass substrate SUB1 can be the observation side (externally exposed side).

The light-shielding film BM is also formed in a peripheral portion in a frame-shaped pattern, and the pattern is formed continuously with the pattern of the matrix portion provided with a plurality of openings in a dot shape. The light shielding film in this portion has the same function as the light shielding film SHF in FIG. The light-shielding film BM in the peripheral portion is a strip spacer SPC-
S is extended outside the sealant SL beyond S to prevent leaked light such as reflected light from the mounting device such as a personal computer from entering the matrix portion. On the other hand, the light-shielding film BM is about 0.3 to 1.0
mm, and is formed so as to avoid the cutting area of the upper transparent glass substrate SUB2.

Color filters FIL (R), FIL
(G) and FIL (B) are formed by coloring a dye on a dyed base material formed of a resin material such as an acrylic resin. FIG. 10 does not show the color filter FIL (B). The color filters FIL (R), FIL
(G) and FIL (B) are formed in stripes at positions facing the pixels, and are dyed into red (R), green (G), and blue (B). This color filter FIL
(R), FIL (G), FIL (B) are transparent pixel electrodes I
The light shielding film B is formed to be large so as to cover all of the TO1.
M is a color filter FIL (R), FIL (G), FI
It is formed inside the periphery of the transparent pixel electrode ITO1 so as to overlap L (B) and the edge of the transparent pixel electrode ITO1.

Color filters FIL (R), FIL
(G) and FIL (B) can also be formed as follows. First, a dyed base material is formed on the surface of the upper transparent glass substrate SUB2, and the dyed base material other than the red filter forming region is removed by photolithography. Thereafter, the dyed base material is dyed with a red dye, fixed, and treated with a red filter FIL.
(R) is formed. Next, by performing similar steps, the green filter FIL (G) and the blue filter FIL
(B) is sequentially formed.

The protective film PSV2 is a color filter FIL
This is provided in order to prevent the dye obtained by dyeing (R), FIL (G), and FIL (B) into different colors from leaking into the liquid crystal layer LC. This protective film PSV2 is formed of a transparent resin material such as an acrylic resin and an epoxy resin.

The common transparent pixel electrode ITO2 is opposed to the transparent pixel electrode ITO1 provided for each pixel on the lower transparent glass substrate SUB1 side, and the optical state of the liquid crystal layer LC is determined by each pixel electrode ITO1 and the common transparent pixel electrode ITO2. Changes in response to a potential difference (electric field) between them. The common transparent pixel electrode ITO2 is configured to apply a common voltage Vcom. Here, the common voltage Vcom is set to an intermediate potential between the low-level drive voltage Vdmin and the high-level drive voltage Vdmax applied to the video signal line, but the power supply voltage of the integrated circuit used in the video signal drive circuit If it is desired to reduce by about half, an AC voltage may be applied.

The gate terminal GTM is made of silicon oxide SIO
It is composed of a chromium Cr layer g1 that has good adhesion to the layer and has higher corrosion resistance than aluminum Al, and a transparent conductive layer d1 that protects the surface and has the same level (same layer and simultaneous formation) as the pixel electrode ITO1. ing. The conductive layers d2 and d3 formed on the gate insulating film GI and on side surfaces thereof
Is left as a result of covering the regions with photoresist so that the conductive layers g2 and g1 are not etched together due to pinholes or the like at the time of etching the conductive layers d2 and d3. In addition, the ITO layer d1 extending rightward beyond the gate insulating film GI is a thorough countermeasure.

The drain terminal DTM constitutes a terminal group Td (subscript omitted) as shown in FIG. 9 and is further extended beyond the cutting line CT1 of the lower transparent glass substrate SUB1 to prevent electrostatic breakdown during the manufacturing process. Therefore, all of them are interconnected by SH
shorted by d.

The drain terminal DTM is formed of two layers of a chromium Cr layer g1 and an ITO layer d1 for the same reason as the gate terminal GTM described above, and is connected to the video signal line DL at a portion where the gate insulating film GI is removed. ing. The semiconductor layer AS formed on the edge of the gate insulating film GI is for etching the edge of the gate insulating film GI into a video signal in a tapered shape. On the drain terminal DTM, of course, the protective film PSV1 is removed for connection with an external circuit.

FIG. 12 is an explanatory diagram of the overall configuration of a direct-view type liquid crystal display device embodying the liquid crystal display device according to the present invention.

This liquid crystal display device describes a specific structure of a liquid crystal display device (liquid crystal display module) in which a liquid crystal panel, a circuit board, a backlight, and other components are integrated.

In FIG. 12, SHD is an upper frame (also referred to as a shield case or metal frame) made of a metal plate, WD is a display window, INS1 to 3 are insulating sheets, PC
B1 to B3 are circuit boards (PCB1 is a drain side circuit board:
A video signal line driving circuit board, PCB2 is a gate side circuit board, PCB3 is an interface circuit board), JN1
Reference numeral 3 denotes a joiner for electrically connecting the circuit boards PCB1 to PCB3, TCP1 and TCP2 denote a tape carrier package, PNL denotes a liquid crystal panel in which a predetermined cell gap is set by the column spacer and the band spacer described in the above embodiment, and POL. Is the upper polarizer, GC is the rubber cushion, ILS
Is a light shielding spacer (corresponding to the light shielding film SHF in FIG. 1),
PRS is prism sheet, SPS is diffusion sheet, GLB
Is a light guide plate, RFS is a reflection sheet, MCA is a lower frame (lower case: mold frame) formed by integral molding of resin, MO is an MCA opening, and BAT is a double-sided adhesive tape. The liquid crystal display device MDL is assembled by stacking the diffusion plate members. The light guide plate G
A light source assembly including a fluorescent tube LP and a reflection sheet LS is installed along one side of LB, and a lamp cable L pulled out from a rubber cushion GC provided at an end of the fluorescent tube LP.
Power is supplied from a backlight power supply (not shown) via a PC. The light guide plate GLB and the light source assembly are combined to form a backlight BL.
Is configured. The light source assembly can be installed on two or four sides of the light guide plate GLB.

This liquid crystal display device (liquid crystal display module M)
DL) has a housing composed of two kinds of storage / holding members of a lower frame MCA and an upper frame SHD, and an insulating sheet IN
S1 to S3, circuit boards PCB1 to PCB3, and liquid crystal panel PNL are stored and fixed, and lower frame MCA storing a backlight composed of light guide plate GLB and the like is combined with upper frame SHD.

Electronic components such as an integrated circuit chip for driving each pixel of the liquid crystal panel PNL are mounted on the video signal line driving circuit board PCB1, and an interface circuit board PCB3 is provided with an image signal from an external host computer. An integrated circuit chip that accepts and receives control signals such as timing signals, and a timing converter (TCON) that processes timing to generate a clock signal, a low-voltage differential signal chip, and other electronic components such as capacitors and resistors Is done.

The clock signal generated by the timing converter is supplied to a drive circuit chip (integrated circuit chip) mounted on the video signal line drive circuit board PCB1.

The interface circuit board PCB3 and the video signal line driving circuit board PCB1 are multilayer wiring boards, and the clock signal line CLL is connected to the interface circuit board PCB3 and the video signal line driving circuit board PC
It is formed as an inner wiring of B1.

The liquid crystal panel PNL has a drain-side circuit board PCB1, a gate-side circuit board PCB2, and an interface circuit board PCB3 for driving TFTs.
Are connected by tape carrier packages TCP1 and TCP2, and the circuit boards are connected by joiners JN1, JN2, JN3.

With this liquid crystal display device, it is possible to obtain a high quality image display without display unevenness.

FIG. 13 is a perspective view of a notebook computer for explaining a mounting example of the liquid crystal display device shown in FIG.

The notebook computer (portable personal computer) includes a keyboard section (main body section) and a display section hingedly connected to the keyboard section. Keyboard and host (host computer), CP
U and other signal generation functions, and the display unit has a liquid crystal panel P
Drive circuit boards FPC1 and FPC
2. A PCB on which the control chip TCON is mounted, and an inverter power supply board IV serving as a backlight power supply are mounted.

Each of the above electronic devices equipped with the liquid crystal display device according to the present invention has a very small change in the cell gap of the liquid crystal panel, so that it is possible to obtain a high quality image display without display unevenness.

[0114]

As described above, according to the present invention,
When a stress is generated between the columnar spacer and the opposing substrate due to a difference in thermal expansion coefficient between the driving substrate as the first substrate and the opposing substrate as the second substrate, the contact area between the columnar spacer and the opposing substrate is small, so that a liquid crystal layer is formed. The contact portion easily shifts while maintaining the gap (cell gap).

In the manufacturing process, even if there are fine irregularities on the surface of the opposing substrate as the second substrate, or if there is a slight difference in the height of the columnar spacer, Even if local stress is applied to the columnar spacer and the opposing substrate during bonding, the contact area between them is small, so that the columnar spacer is easily crushed at the contact portion, and the circuits, electrodes, and other functions formed on the substrate. Does not destroy the film.

As described above, according to the present invention, detachment of the columnar spacers and various destructions caused by the columnar spacers during pressing between the substrates are avoided, and a highly reliable and high quality liquid crystal display device is provided. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a liquid crystal panel for explaining one embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a schematic sectional view of a liquid crystal panel illustrating a second embodiment of the liquid crystal display device according to the present invention.

FIG. 3 is a plan view illustrating an arrangement of columnar spacers of the liquid crystal panel shown in FIG. 1 or FIG.

FIG. 4 is a schematic view of a micrograph of a cross section of a columnar spacer according to the present invention.

FIG. 5 is a schematic diagram illustrating a state in which two substrates are pressed against each other and bonded together using the columnar spacer of the present embodiment.

FIG. 6 is a plan view illustrating another configuration example of the liquid crystal panel of the liquid crystal display device according to the present invention.

FIG. 7 is an explanatory diagram of an overall configuration of a projection type liquid crystal display device embodying the liquid crystal display device according to the present invention.

FIG. 8 is a schematic diagram for explaining a configuration example of a projection type liquid crystal display device configured using the liquid crystal display device described in FIG. 7;

FIG. 9 is a plan view of a liquid crystal panel included in an active matrix type liquid crystal display device.

10 is an enlarged plan view of the vicinity of a seal portion SL corresponding to the upper left corner of the liquid crystal panel shown in FIG.

FIG. 11 is a sectional view of a main part of a liquid crystal panel constituting an active matrix type liquid crystal display device to which the present invention is applied.

FIG. 12 is an explanatory diagram of the overall configuration of a direct-view type liquid crystal display device embodying the liquid crystal display device according to the present invention.

FIG. 13 is a perspective view of a notebook computer for explaining a mounting example of the liquid crystal display device shown in FIG.

[Explanation of symbols]

USB Upper substrate (counter substrate) as first substrate DSB Lower substrate (drive substrate) as second substrate LC Liquid crystal layer composed of liquid crystal composition SUB2 Glass substrate constituting counter substrate ITO-C transparent electrode (Common electrode or counter electrode) ORI2 Upper alignment film SUB1 Single crystal silicon substrate or active matrix substrate constituting drive substrate AL-P Pixel electrode ORI1 Lower alignment film TM Terminal PSV1 Protective film SPC-P Columnar spacer SPC- S Strip spacer SL Sealant SHF Light shielding film.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kazuya Takemoto 3300 Hayano Mobara-shi, Chiba Prefecture Hitachi, Ltd.Electronic Device Division (72) Inventor Toshio Miyazawa 3300 Hayano Mobara-shi, Chiba Hitachi, Ltd.Electronics Inside the Device Division (72) Inventor Hideki Nakagawa 3300 Hayano, Mobara City, Chiba Prefecture Inside Electronic Device Division, Hitachi, Ltd. (72) Inventor Kenji Kitajima 3681 Hayano, Mobara City, Chiba Prefecture Hitachi Device Engineering Co., Ltd. (72) Inventor Katsutoshi Saito 3300 Hayano, Mobara-shi, Chiba Pref.Electronic Device Division, Hitachi, Ltd. QA14 QA16 TA02 5C0 94 AA03 AA36 AA47 AA48 AA55 BA03 BA43 CA19 DA12 EA04 EA05 EC03 EC04 ED14 FB01 FB15 GB01 GB10

Claims (2)

[Claims] A first substrate having a large number of pixel electrodes formed in a matrix; a second substrate having a transparent electrode opposed to the first substrate with a predetermined gap;
The liquid crystal layer composed of a liquid crystal composition sealed in the gap between the first substrate and the second substrate, and the alignment of the liquid crystal composition formed on each surface of the first substrate and the second substrate that are in contact with the liquid crystal layer are controlled. An alignment film, and a plurality of columnar spacers formed in a display area of the first substrate so as to protrude so as to maintain a facing gap between the second substrate and the second substrate at a predetermined value. 2. A liquid crystal display device according to claim 1, wherein the area of the tip portion in contact with the inner surface is smaller than the area of the base portion connected to the inner surface of the first substrate. 2. The liquid crystal display device according to claim 1, wherein said columnar spacer is made of a resist material formed by photolithography.