JP2000172192A - Liquid crystal display device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a liquid crystal display device capable of being made narrow in its frame part and low in its manufacturing cost. SOLUTION: A substrate 11 is divided into one or plural panel areas 51 and control circuit areas 52. A data bus line, a gate bus line, and at least TFT or a picture element electrode and a data driver circuit or a gate driver circuit are formed in the panel area 51. A control circuit is formed in the control circuit area 52. The substrate 11 is divided and the substrate having the panel area 51 is connected with the substrate having the control circuit area 52 by a flexible cable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix type liquid crystal display device having a polysilicon thin film transistor (TFT) and a method of manufacturing the same.

[0002]

2. Description of the Related Art An active matrix type liquid crystal display device is provided with a switch which is turned off when not selected and cuts off a signal in each pixel to prevent crosstalk. It shows excellent display characteristics as compared with. In particular, T as a switch
Since the liquid crystal display device using the FT has a high driving capability of the TFT, the liquid crystal display device has excellent display characteristics comparable to a CRT (Cathode-Ray Tube).

Generally, a liquid crystal display device has a structure in which liquid crystal is sealed between two transparent substrates. Of the two opposing surfaces (opposing surfaces) of the transparent substrate, an opposing electrode, a color filter, an alignment film and the like are formed on one surface side, and a TFT, a pixel electrode, and an alignment film are formed on the other surface side. A film or the like is formed. Further, a polarizing plate is attached to a surface of each transparent substrate opposite to the facing surface. These two polarizing plates are arranged, for example, such that the polarization axes of the polarizing plates are orthogonal to each other. According to this, a mode in which light is transmitted when no electric field is applied and light is blocked when an electric field is applied, That is, a normally white mode is set. On the contrary, when the polarization axes of the two polarizing plates are parallel, a normally black mode is set. Hereinafter, a transparent substrate having a TFT, a pixel electrode and the like is called a TFT substrate, and a transparent substrate having a counter electrode and the like is called a counter substrate.

In recent years, TFTs using thin-film polysilicon formed by a low-temperature process have been developed and used in liquid crystal display devices. When a TFT is formed by a low-temperature process, there is an advantage that an inexpensive glass substrate can be used as a transparent substrate. In addition, since the polysilicon TFT has a higher driving capability and can be miniaturized as compared with the amorphous silicon TFT, there is an advantage that the aperture ratio is improved and a bright image can be obtained. Furthermore, in the case of an amorphous silicon TFT, the driving speed is slow, so it was necessary to separately prepare a driving IC and connect it to the liquid crystal display panel.
Since the driving speed of the polysilicon TFT is high, a driving (driver) circuit can be formed on a glass substrate. Thus, there is no need to separately manufacture the driving IC, and the manufacturing cost can be reduced.

In recent years, a technique called a system-on-panel in which not only a drive circuit but also a control circuit is formed on a glass substrate has been proposed in order to further increase the efficiency of the manufacturing process of a liquid crystal display device.

FIG. 8 is a schematic diagram showing a TFT substrate of a liquid crystal display device using this technique. On the glass substrate 61,
A display area 62, a data driver circuit 63, a gate driver circuit 64, and a control circuit 65 are provided. The display area 62 is an area in which a plurality of pixel electrodes are arranged in a matrix, and a data bus line and a gate bus line are arranged between the pixel electrodes. The counter substrate is formed to have substantially the same size as the display area 62, and the display area 6
2 and are arranged opposite to each other.

The control circuit 65 receives a video signal from a video signal output device such as a personal computer and generates a data signal and a timing signal (data start signal, data clock signal, gate start signal, gate clock signal, etc.). These signals are transmitted to the data driver circuit 6
3 and the gate driver circuit 64.

The data driver circuit 63 is a circuit for supplying a data signal to a data bus line in the display area 62, and the gate driver circuit 64 is a circuit for supplying a scanning signal to the gate bus line. By supplying a data signal and a scanning signal from the data driver circuit 63 and the gate driver circuit 64 to the data bus line and the gate bus line at a predetermined timing, a desired image can be displayed on the liquid crystal display device.

[0009]

However, in the liquid crystal display device shown in FIG. 8, not only the data driver circuit 63 and the gate driver circuit 64 but also the control circuit 65 are formed on the glass substrate 61. The area of the portion outside 62 is inevitably large. Glass substrate 61
The portion outside the display area 62 is referred to as a picture frame. It is said that the narrower the picture frame, the smaller the size of the liquid crystal display device and the better the appearance as a product.

In the liquid crystal display device shown in FIG. 8, when a failure occurs in any one of the display area 62, the data driver circuit 63, the gate driver circuit 64, and the control circuit 65, the other circuits are not normally operating. Nevertheless, it cannot be used as a liquid crystal display device. For this reason, the method of forming these circuits on one glass substrate lowers the yield and increases the product cost.

Accordingly, an object of the present invention is to provide a liquid crystal display device having a narrow frame portion and capable of reducing the manufacturing cost, and a method of manufacturing the same.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide a display area having a plurality of data bus lines and a plurality of gate bus lines intersecting the data bus lines, and supplying a data signal to the data bus lines. A data driver circuit, a scan driver circuit that supplies a scan signal to the gate bus line, and a control circuit that supplies a signal indicating an output timing of the data signal and the scan signal to the data driver circuit and the scan driver circuit. A liquid crystal display device having at least one of the data driver circuit and the scan driver circuit and the display area on a first substrate made of glass or quartz;
The liquid crystal display device is characterized in that the control circuit is provided on a second substrate made of glass or quartz, and the first substrate and the second substrate are connected by a flexible cable. .

Further, the above-mentioned problem is solved by dividing a substrate into one or a plurality of sets of panel areas and control circuit areas, and in the panel area, a plurality of data bus lines and a plurality of data bus lines intersecting these data bus lines. A gate bus line, a plurality of thin film transistors connected to the gate bus line and the gate bus line, a plurality of pixel electrodes respectively connected to the thin film transistors, and at least one of the data bus line and the gate bus line. Forming a driver circuit for supplying a signal, and at the same time, forming a control circuit for supplying a signal to the driver circuit in the control circuit region, cutting the substrate, and forming a first circuit having the panel region. The substrate and the second substrate having the control circuit area are individually separated, and the first substrate and the second substrate are separated from each other. It is solved by a method of manufacturing a liquid crystal display device according to claim to connect at-smoking cable.

The operation of the present invention will be described below.

In the method of the present invention, first, one substrate is divided into one or a plurality of sets of panel areas and control circuit areas. Then, a data bus line, a gate bus line, and a pixel electrode are formed in the panel area, and a driver circuit is formed. At the same time, a control circuit is formed in the control circuit area. Thereafter, the substrate is cut and separated into a first substrate having the panel region and a second substrate having the control circuit region, and the first and second substrates are connected by a flexible cable.

As described above, in the method of the present invention, the first
And the second substrate are formed at the same time, so that the manufacturing efficiency is good,
Manufacturing costs can be reduced. In addition, the same reliability can be expected for each element of the manufactured display device. Further, since the second substrate having the control circuit is separated from the first substrate, a frame portion can be narrowed, and a liquid crystal display device excellent in design can be obtained.

In the device of the present invention, the first substrate having the display area and the driver circuit and the second substrate having the control circuit are both formed on a substrate made of glass or quartz. Therefore, the first and second methods are performed by the above method.
Can be formed simultaneously. Further, since the control circuit is separated from the first substrate, the frame portion of the first substrate can be narrowed. Further, since the first substrate and the second substrate are connected by the flexible cable, the second substrate can be arranged, for example, on the back side of the backlight unit or outside the display area of the first substrate.

[0018]

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

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
It is a side view which shows the liquid crystal display device of Embodiment.

The liquid crystal display panel 1 is disposed on a phosphor screen (a side from which light is output) of the backlight unit 2.
The control circuit board 4 is disposed on the rear side of the backlight unit 2. The liquid crystal display panel 1 and the control circuit board 4 are electrically connected via the flexible cable 3. One or a plurality of cold cathode tubes are accommodated in the backlight unit 2.

FIG. 2 is a sectional view of a display area of the liquid crystal display panel 1, and FIG. 3 is a plan view of a TFT substrate of the liquid crystal display panel.

The liquid crystal display panel 1 is composed of a TFT substrate 10 and a counter substrate 20 which are arranged to face each other, and a liquid crystal 29 sealed between the TFT substrate 10 and the counter substrate 20.

As shown in FIGS. 2 and 3, the TFT substrate 10 comprises a substrate 11a made of glass or quartz (hereinafter simply referred to as a "glass substrate") and a data bus line 12 formed on the glass substrate 11a. , Gate bus line 1
3, the pixel electrode 14, the TFT 15, and the like.
The data bus lines 12 and the gate bus lines 13 are arranged orthogonal to each other, and are electrically insulated by an insulating film (not shown) formed therebetween. A rectangular area surrounded by the data bus line 12 and the gate bus line 13 is a pixel. Each pixel has a transparent pixel electrode 14 made of indium-tin oxide (hereinafter referred to as ITO) and a TFT 15. Is arranged. The TFT 15 includes a protruding portion (gate) of the gate bus line 13 and a polysilicon film 16 selectively formed thereon via an insulating film. TFT1
The source of the TFT 5 is connected to the pixel electrode 14 via a contact hole (not shown), and the drain of the TFT 15 is connected to the data bus line 12 via a contact hole (not shown).

The polysilicon film 16 is formed on the glass substrate 11a.
An amorphous silicon film is formed thereon by a CVD (Chemical Vapor Deposition) method, and the amorphous silicon film is irradiated with a laser beam to change the amorphous into polysilicon.

As shown in FIG. 2, an alignment film 17 is formed on the upper side of the glass substrate 11a so as to cover the pixel electrode 14. The alignment film 17 is made of, for example, polyimide, and its surface is subjected to an alignment process to determine the alignment direction of the liquid crystal molecules when no voltage is applied. As a typical method of the alignment treatment, a rubbing method in which a surface of an alignment film is rubbed in one direction by a cloth roller is known.

On the other hand, the opposite substrate 20 is a glass substrate 21
And a color filter 22, a black matrix 23, a counter electrode 24, an alignment film 25, and the like formed on the lower surface side of the glass substrate 21. The color filter 22 has three colors of red (R), green (G), and blue (B).
There are different types, and one color filter 22 faces one pixel electrode 14. A black matrix 23 is formed between these color filters 22. The black matrix 23 is made of a metal thin film that does not transmit light, such as chrome (Cr).

Under the color filter 22 and the black matrix 23, a transparent counter electrode 24 made of ITO is formed. Under the counter electrode 24, an alignment film 25 is provided.
Are formed. The surface of the alignment film 25 is also subjected to an alignment process.

A spherical spacer (not shown) is arranged between the TFT substrate 10 and the opposing substrate 20, so that the distance between the TFT substrate 10 and the opposing substrate 20 is kept constant. Further, a polarizing plate (not shown) is disposed below the TFT substrate 10 and above the opposing substrate 20, respectively. These polarizing plates are arranged so that the polarization axes are orthogonal to each other.

FIG. 4 is a block diagram showing a circuit configuration of the liquid crystal display device.

As shown in FIG. 2, the liquid crystal display panel 1 has a display area 31 in which a plurality of pixels are arranged in a matrix.
And a data driver circuit 32, a gate driver circuit 33, and a terminal electrode 34 arranged outside the display area 31.
Are provided. The display area 31, the data driver circuit 32, the gate driver circuit 33, and the terminal electrode 34 are provided on the same glass substrate 11a, and the TFTs forming the data driver circuit 32 and the gate driver circuit 33 are arranged in the display area 31. Formed at the same time as the TFTs in FIG. In addition, between the terminal electrode 34 and the data driver circuit 32 and the gate driver circuit 33, and between the data driver circuit 32 and the data bus line 1 of the display area 31.
2, the gate driver circuit 33 and the display area 3
One gate bus line 13 is connected to the data bus line 12 or the wiring formed simultaneously with the gate bus line 13.

The control circuit board 4 includes a timing generation circuit 41 and a data formation circuit 4 formed on the glass substrate 11b.
2 and a terminal electrode 43. An R (red), G (green), B (blue) signal, a vertical synchronizing signal Vs, and a horizontal synchronizing signal Hs are input to the control circuit board 4 from a video output device such as a personal computer.

The timing generating circuit 41 converts the data clock signal DC from the vertical synchronizing signal Vs and the horizontal synchronizing signal Hs.
LK, a data clock inversion signal / DCLK, a data start signal DSI, a gate clock signal GCLK, a gate clock inversion signal / GCLK, and a gate start signal GSI are generated and output. The data start signal DSI is a signal indicating the start of one horizontal synchronization period, and the gate start signal GSI is a signal indicating the start of one vertical synchronization period.

The data forming circuit 42 receives the R, G, and B signals from the video display device, and receives the horizontal synchronizing signal Hs and the data clock signal DCLK from the timing generating circuit 41.
And a data clock inversion signal / DCLK to generate data signals D _{1 to} D _N (N is the number of pixels in the horizontal direction) for one horizontal synchronization period, and output them in parallel at a timing synchronized with the horizontal synchronization signal Hs. .

The flexible cable 3 connecting the liquid crystal display panel 1 and the control circuit board 4 is joined to the terminal electrodes 34 and 43. Then, the data driver circuit 32 sends the data signals D _{1 to} D _N , the data start signal DSI, the data clock signals DCLK and / DCLK from the control circuit board 4.
And supplies data signals D _{1 to} D _N to each data bus line 12 of the display area 31 at a timing synchronized with the data start signal DSI and the data clock signals DCLK and / DCL. Further, the gate driver circuit 33 includes the control circuit board 4
From the gate start signal GSI, the gate clock GCLK, / G
CLK is input, and a scanning signal is sequentially supplied to each gate bus line 13 of the display area 31 at a timing synchronized with the gate start signal GSI and the gate clocks GCLK and / GCLK.

FIGS. 5 and 6 are views showing a method of manufacturing a liquid crystal display device according to an embodiment of the present invention in the order of steps.

First, as shown in FIG.
Are divided into a panel area 51, a control circuit area 52, and a custom integrated circuit area 53, and a predetermined circuit is formed in each area. That is, as shown in FIG. 3, the data bus line 12, the gate bus line 1
3, a pixel electrode 14, a TFT 15, etc., and a data driver circuit 32, a gate driver circuit 33, and a terminal electrode 34 as shown in FIG. At the same time, the control circuit, ie, the timing generation circuit 41
In addition, a TFT and the like constituting the data forming circuit 42 and the terminal electrode 43 are formed, and an integrated circuit constituting a part of the control circuit is formed in the custom integrated circuit region 53. In this example,
A panel area 51, a control circuit area 52, and a custom integrated circuit area 53 for four sets are provided on one glass substrate 11. The panel area 51 and the control circuit area 5
2 and the integrated circuit region 53 are arranged independently of each other. That is, the panel region 51, the control circuit region 52, and the integrated circuit region 53 are not electrically connected.

Next, the circuits formed in the panel area 51, the control circuit area 52, and the custom integrated circuit area 53 are inspected. Those determined to be defective are excluded from the next step.

Next, the glass substrate 11 is cut to separate each panel region 51, control circuit region 52, and custom integrated circuit region 53 individually. The substrate including the panel region 51 becomes the TFT substrate 10, the substrate having the control circuit region 52 becomes the control circuit substrate 4, and the substrate having the integrated circuit region 53 becomes the custom integrated circuit mounted on the control circuit substrate 4.

After that, the TFT substrate 10 and the separately prepared counter substrate 20 (see FIG. 2) are combined, and liquid crystal is sealed between the two to form the liquid crystal display panel 1.

Next, as shown in FIG. 6, a custom integrated circuit 53a (a substrate having an integrated circuit area 53) is mounted on the control circuit board 4 to complete the control circuit board 4. The liquid crystal display panel 1 is electrically connected with the flexible cable 3. Thereafter, as shown in FIG. 1, the liquid crystal display panel 1 is arranged on the fluorescent screen side of the backlight unit 2, and the control circuit board 4 is arranged on the back surface side.
Thereby, the liquid crystal display device is completed.

In the present embodiment, one glass substrate 11 is divided into a plurality of sets of a panel region 51, a control circuit region 52, and an integrated circuit region 53, and a TFT, a wiring, and the like are formed simultaneously in these regions. The manufacturing efficiency is good and the manufacturing cost can be reduced. Also, the same level of reliability can be expected for each element circuit. Further, since one or a plurality of sets of components of the liquid crystal display device are formed on one glass substrate 11, there is an advantage that component management becomes easy. Further, in the present embodiment, the liquid crystal display panel 1
The liquid crystal display panel 1 is separated from the control circuit board 4.
Can be narrowed. Thereby, the appearance is improved, and a liquid crystal display device excellent in design is obtained.

(Second Embodiment) FIG. 7 shows a second embodiment of the present invention.
It is a side view which shows the liquid crystal display device of Embodiment. Note that this embodiment is different from the first embodiment in that the position where the control circuit board is disposed is different, and the other parts are basically the same as the first embodiment. The description of the parts to be performed is omitted.

In this embodiment, the control circuit board 4
“a” is the fluorescent screen side of the backlight unit 2, which is disposed at a position facing the frame portion of the liquid crystal display panel 1. The control circuit board 4a and the liquid crystal display panel 1 are electrically connected by the flexible cable 3a. The structure and manufacturing method of the liquid crystal display panel 1 are the same as those of the first embodiment. Also in the present embodiment, the same effect as in the first embodiment can be obtained.

[0044]

As described above, according to the device of the present invention, the first substrate having the display area and the driver circuit is provided with:
Since the second substrate having the control circuit is connected to the second substrate by a flexible cable, the width of the first substrate outside the display area can be reduced. As a result, a liquid crystal display device which can be reduced in size and has an excellent design can be obtained.

According to the method of the present invention, a substrate such as glass or quartz is divided into a panel region and a control circuit region,
After a predetermined circuit is formed in each region, the first substrate having a panel region and the second substrate having a control circuit region are separated from each other, so that manufacturing efficiency is high and manufacturing cost can be reduced. Also, the same level of reliability can be expected for each element circuit. Furthermore, the outer portion of the display area of the first substrate can be narrowed, and a liquid crystal display device which is easy to miniaturize and excellent in design can be manufactured.

[Brief description of the drawings]

FIG. 1 is a side view showing a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a display area of the liquid crystal display panel.

FIG. 3 is a plan view of a TFT substrate of the liquid crystal display panel.

FIG. 4 is a block diagram illustrating a circuit configuration of a liquid crystal display device.

FIG. 5 is a diagram (part 1) illustrating the method of manufacturing the liquid crystal display according to the embodiment of the present invention.

FIG. 6 is a diagram (part 2) illustrating the method of manufacturing the liquid crystal display device according to the embodiment of the present invention.

FIG. 7 is a side view showing a liquid crystal display device according to a second embodiment of the present invention.

FIG. 8 is a schematic diagram showing a TFT substrate of a conventional liquid crystal display device.

[Explanation of symbols]

 1,61 liquid crystal display panel, 2 backlight unit, 3,3a flexible cable, 4,4a control circuit board, 10 TFT substrate, 11, 11a, 11b, 21 glass substrate, 12 data bus line, 13 gate bus line, 14 Pixel electrode, 15 TFT, 20 opposed substrate, 31 display area, 32, 63 data driver circuit, 33, 64 gate driver circuit, 41 timing generation circuit, 42 data formation circuit, 51 panel area, 52 control circuit area, 53 integrated circuit region.

Continued on front page F-term (reference) 2H092 GA50 JA24 JB22 JB31 KA04 MA07 MA30 NA25 PA01 PA06 PA13 5G435 AA00 AA17 AA18 BB12 BB15 CC09 EE25 EE33 EE36 EE37 EE47 KK05

Claims (4)

[Claims] A display area provided with a plurality of data bus lines and a plurality of gate bus lines intersecting the data bus lines; a data driver circuit for supplying a data signal to the data bus lines; A liquid crystal display device comprising: a scan driver circuit for supplying a scan signal to the liquid crystal display device; and a control circuit for supplying the data driver circuit and a signal indicating the output timing of the scan signal to the scan driver circuit. Wherein the display region is provided on at least one of the data driver circuit and the scan driver circuit on a first substrate made of, and the control circuit is provided on a second substrate made of glass or quartz; The first substrate and the second substrate are connected by a flexible cable. Liquid crystal display device. 2. A backlight unit for emitting light, wherein the first substrate is disposed on a light emitting surface side of the backlight unit, and wherein the second substrate is provided on the light emitting surface of the backlight. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is disposed on an opposite surface side. 3. A backlight unit for emitting light, wherein the first substrate is disposed on a light emitting surface side of the backlight unit, and wherein the second substrate is provided on the light emitting surface of the backlight unit. 2. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is disposed on a side of the first substrate so as to face a portion outside the display region of the first substrate. 4. A substrate is divided into one or a plurality of sets of panel areas and control circuit areas, and a plurality of data bus lines, a plurality of gate bus lines intersecting these data bus lines are provided in the panel area, A gate bus line, a plurality of thin film transistors connected to the gate bus line, a plurality of pixel electrodes respectively connected to the thin film transistors, and a driver for supplying a signal to at least one of the data bus line and the gate bus line Forming a control circuit for supplying a signal to the driver circuit in the control circuit region; cutting the substrate to form a first substrate having the panel region; Separating the second substrate having the region individually, connecting the first substrate and the second substrate with a flexible cable Method of manufacturing a liquid crystal display device which is characterized in that.