JPH10133232A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an inexpensive liquid crystal display device with a drive means reducing a difference between an output pitch of a drive element and a transparent conductive film electrode pitch of a display area and with excellent reliability and productivity compared with the case of an LSI drive circuit element by a usual semiconductor silicon substrate. SOLUTION: At least one side between a signal voltage application element and a scan voltage application element is made the drive circuit element consisting of glass material constituting a drive circuit by a thin film transistor structure, and is mounted on at least one side peripheral part between a first glass substrate 2 and a second glass substrate 3, and a width of a drive circuit channel in the drive circuit element is made nearly equal to the pitch size of the scan electrode or the signal electrode of the display area of a liquid crystal display element 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device using a simple matrix type liquid crystal panel as a display element.

[0002]

2. Description of the Related Art In a liquid crystal display device using a matrix type liquid crystal panel as a display element, as a conventional technique of a signal voltage or scanning voltage applying means, a CMO on a semiconductor silicon substrate is used.
There is a mounting method using an LSI chip on which a drive circuit having an S configuration is formed in a form shown in FIG. 5 or FIG.

[0005] The form shown in FIG. 5 is called tape automated boarding mounting (hereinafter referred to as TAB mounting).
The liquid crystal display element 1 has an effective display area 1a, a peripheral black matrix section (hereinafter, referred to as a BM section) and a seal section 1b. Is provided. As a scanning voltage applying means, an LSI element 4 made of a semiconductor silicon substrate is mounted on a tape carrier package (hereinafter, referred to as TCP) 5, and the TCP 5 has an output terminal side on the first glass substrate 2. Are connected to a multilayer printed wiring board 6 for supplying a voltage and various control signals.

Similarly, as a signal voltage applying means, an LSI element 7 made of a semiconductor silicon substrate is mounted on a TCP 8, its output terminal side is connected to a signal electrode on a second glass substrate 3, and its input side is connected to a voltage and voltage. Each is connected to a multilayer printed wiring board 9 for supplying data signals and the like. As a connection wire bundle 10 for connecting the multilayer printed wiring board 6 on the scanning electrode side and the multilayer printed wiring board 9 on the signal electrode side, a flexible printed wiring board (hereinafter, referred to as FPC) or a flexible flat cable (hereinafter, referred to as FFC) is used. In many cases, this is not always necessary, and various configurations can be taken depending on the circuit configuration and the arrangement thereof.

[0005] The form of the signal voltage application means in FIG. 6 is called chip-on-glass mounting (hereinafter referred to as COG mounting).
The configuration of the liquid crystal display element 1 is the same as that of FIG. An LSI element 7 made of a semiconductor silicon substrate is directly arranged and mounted on the second glass substrate 3, and its output terminal side is connected to a signal electrode on the second glass substrate 3. The input terminal is connected to one end of a relay electrode pattern also provided on the second glass substrate 3. A plurality of output terminals 11 a of the multilayer printed wiring board 11 for supplying a voltage, a data signal and the like are connected to the other end of the relay electrode pattern on the second glass substrate 3.

The multilayer printed wiring board 11 is provided with a material for reducing the longitudinal stress of the multilayer printed wiring board 11 generated at a connection portion due to a difference in thermal expansion coefficient between the substrate material and the second glass substrate 3. A constricted portion 11b is provided to facilitate alignment during mounting.

As a method of connecting the LSI element 7 and the electrode pattern on the second glass substrate 3, anisotropic conductive film method (hereinafter referred to as ACF method), wire bonding method, A soldering method or the like is used.

FIG. 6 shows the same TAB mounting as that of FIG. 5 as the form of the scanning voltage applying means. However, it is also possible to employ the same COG mounting as the signal voltage applying means of FIG.

In both FIGS. 5 and 6, the signal voltage applying means is arranged on one of the long sides of the second glass substrate 3. Screen driving method (Dual Sc
an). Further, the scanning voltage application means is arranged not only on one side of the short side of the first glass substrate 2 but also on the other side, and a screen division such as a two-sided power supply system in which a scanning voltage is applied from both sides to the same electrode. (Therefore, there are various types of arrangement of the electrode applying means and the arrangement of the voltage applying means and the power supply system.

In such a conventional structure, a liquid crystal display element in a simple matrix type liquid crystal display device needs to have conductivity and transparency as an electrode due to its principle. (Hereinafter referred to as a transparent conductive film) is used. In a color liquid crystal panel that is becoming popular, RG
The method of providing a three-color color filter of B is the mainstream, but the color filter often takes the form of a vertical stripe because of its sharpness such as character display. Therefore, RGB
Since the signal electrode width and the scan electrode width in the trio are set to be substantially equal, the signal electrodes have a density three times as high as the scan electrodes. At present, the pitch, film width, and space of the transparent conductive film in the display area are as shown in Table 1, depending on the display size and the display density.

[0011]

[Table 1]

This pitch is about 0.150 to the practical size of one pixel of three colors RGB on the liquid crystal display element.
It is equal to 0.390 mm.

On the other hand, the arrangement pitch of the output terminals of the LSI formed on the semiconductor silicon substrate for driving the liquid crystal element depends on the characteristics, cost and productivity of the LSI itself, TCP, and the like.
The practical pitch is 50 to 130 μm from the lower limit of the connection technology with the semiconductor device, and the longitudinal dimension of the LSI element is limited in terms of its strength and production equipment.

Therefore, each electrode of the liquid crystal display element and the driving L
For electrical connection with each drive circuit channel in the SI, it is necessary to solve the mismatch between the pitch of the transparent conductive film in the display area and the pitch of the output electrodes of the LSI element.

The case of TAB mounting will be described with reference to FIG. In FIG. 7, reference numeral 2a denotes a transparent conductive film in a display area on the first glass substrate 2, 2b denotes a BM portion and a sealing portion, 2c denotes a lead portion of the transparent conductive film, and 2d denotes a connection portion between the transparent conductive film and a TCP output terminal. It is. Reference numeral 5a denotes a copper foil pattern portion for adjusting the pitch on the TCP, and 5b denotes a connection portion with the output terminal of the LSI element 4. As shown in FIG. 7, the mismatch between the pitch of the transparent conductive film in the display area and the pitch of the output electrode of the LSI element is caused by (A) pitch shrinkage in the lead portion of the transparent conductive film,
And (B) the present situation is to adjust and solve by one or both of pitch expansion by copper foil pattern of TCP.

The case of COG mounting will be described with reference to FIG. In FIG. 8, 3a is a transparent conductive film in a display area on the second glass substrate 3, 3b is a BM portion and a seal portion,
c is a lead portion of the transparent conductive film, 3d is a transparent conductive film and LS
The connection portion 3e of the I output terminal is a relay electrode pattern portion of a transparent electrode film connecting the input terminal of the LSI element 7 and the output terminal portion of the multilayer printed wiring board 11. In the case of COG mounting, as is apparent from FIG. 8, it is necessary to execute pitch contraction only at the lead-out portion of the transparent conductive film, which is a major problem. The driving LSI element 7 as the signal voltage applying means is used more frequently than the scanning voltage applying LSI element 4 due to the relationship between the vertical and horizontal aspect ratios and the display density. Increasing the number has been implemented as one of the cost reduction measures in order to increase the density and increase the screen size. However, due to the difference in pitch and the restriction on the LSI size, there are limits to the cost reduction measures.

[0017]

SUMMARY OF THE INVENTION As described above, TAB
In the case of mounting, since the transparent conductive film such as ITO has a high resistance value, if the pitch shrinkage of the transparent conductive film is increased on both the signal electrode side and the scanning electrode side, the difference in electrode resistance between the center and both ends in the divided block is increased. , Display quality deteriorates, such as uneven brightness. Even if the film width of the lead portion is devised, there is naturally a limit due to film forming accuracy and the like.
Inevitably, the pitch of the copper foil pattern portion 5a for pitch adjustment as well as the length in the longitudinal direction of the TCP increases, and the area of the TCP increases, thus increasing the cost. There is.

In the case of COG mounting, wiring for signal transmission between adjacent LSI elements on the second glass substrate 3 may be provided even if a relay electrode pattern of a transparent conductive film is provided between the LSI elements. Since the distance between the LSI elements is long and the resistance value of the transparent electrode is too large, it has to be performed through a multilayer printed wiring board.

On the scanning voltage application side, the pitch difference is larger than that on the signal voltage application side, and the distance between LSI elements becomes longer, so that COG mounting is impractical.

In view of the above, an object of the present invention is to provide a liquid crystal display device of a driving means which is inexpensive and has high productivity.

[0021]

In order to solve the above-mentioned problems, the present invention provides a signal voltage applying element and a scanning voltage applying element formed of a glass substrate on which a driving circuit having a thin film transistor (hereinafter referred to as TFT) structure is formed. The drive circuit element is mounted on the periphery of the first or second glass substrate of the liquid crystal display element.

The number of drive circuit elements arranged and mounted on one side of the liquid crystal display element is one or a plurality of drive circuit elements, and the width of each drive circuit channel in the drive circuit element is equal to the width of the liquid crystal display element. The size of the signal of the display area of the element or the pitch of the scanning electrode, the length of the drive circuit element, the length of one side of the effective display area of the liquid crystal display element,
It has a dimension divided by the number of driving elements arranged on one side.

Further, when a plurality of drive circuit elements are arranged and mounted on one side, a transparent conductive material is provided on a glass substrate of a liquid crystal display element between the drive circuit elements as signal transmission means between the drive circuit elements. A relay electrode pattern made of a film is provided.

According to the present invention, with the above-described structure, the size of the LSI element and the number of drive circuit channels are not restricted, and the display density and the display size of the liquid crystal display element can be adjusted.
The number of drive circuit channels per drive circuit element and the number of drive circuit elements per side can be relatively freely selected and optimized in consideration of cost, production, and the like. By making the longitudinal dimension as close as possible to the block size of the display element (making the width dimension of each channel of the drive circuit close to the electrode pitch of the liquid crystal display element), the pitch shrinkage of the lead portion of the transparent conductive film is almost eliminated. Therefore, it is possible to realize a liquid crystal display device that does not cause deterioration of display quality (block unevenness or the like).

Further, while the LSI element is opaque, in the present invention, the use of alignment marks in the pattern formation by photolithography is required because of the transparency of the glass substrate.
There is an advantage that alignment at the time of mounting and inspection can be easily performed by seeing through from both sides. At the same time, since the thermal expansion coefficients of the glass substrates are the same or relatively close to each other, even if the longitudinal dimension of the drive circuit element is designed to be large,
Sufficient reliability against thermal shock and the like can be ensured.

In connection with signal transmission between the drive circuit elements, the number of wirings and the number of output terminals of the printed wiring board can be reduced through the relay electrode pattern formed of the transparent conductive film.

Therefore, with the configuration of the present invention described above, it is possible to obtain an inexpensive liquid crystal display device of driving means with high productivity.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, a plurality of vertical band-shaped signal electrodes made of a transparent conductive film and a plurality of horizontal band-shaped scanning electrodes made of a transparent conductive film are provided. A liquid crystal display element having a pair of first and second glass substrates facing each other and having a liquid crystal material sealed in a gap between the opposed glass substrates, and a signal voltage applying element connected to the signal electrode and applying a signal voltage And a scanning voltage applying element connected to the scanning electrode and applying a scanning voltage, wherein at least one of the signal voltage applying element and the scanning voltage applying element is TF
The present invention can be implemented by mounting a drive circuit element made of a glass material on which a drive circuit having a T configuration is formed around at least one of the first and second glass substrates of the liquid crystal display element.

Accordingly, the number of drive circuit channels per drive circuit element and the number of drive circuit elements per side can be selected relatively freely without being restricted by the size of the LSI element and the number of drive circuit channels, and the productivity is improved. , Can optimize economics. Furthermore, the drive circuit element is a glass material, and because of its transparency, not only is the alignment at the time of mounting and easy to inspect, but also the thermal expansion coefficients of the glass substrates are the same or relatively close to each other. Even if the longitudinal dimension of the drive circuit element is designed to be large, the reliability against thermal shock can be sufficiently ensured.

Further, according to the present invention, the driving circuit element is disposed on one side of the liquid crystal display element,
By arranging at least one or more and making the longitudinal dimension of one drive circuit element as close as possible to the block size of the display element, pitch shrinkage in the transparent conductive film can be almost eliminated, so that the display quality ( A liquid crystal display device that does not cause deterioration of block unevenness or the like can be realized.

Further, according to the present invention, as a connecting means for transmitting a signal between drive circuit elements, a relay of a transparent conductive film on the glass of the liquid crystal display element between the drive circuit elements is provided. The provision of the electrode patterns eliminates the need to provide wiring and output terminals of the multilayer printed wiring board for signal transmission between drive circuit elements, and can reduce costs and save space.

[0032]

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

FIGS. 1 and 2 are plan views of a main part showing the structure of the liquid crystal display device of the present invention. In FIGS. 1 and 2, the liquid crystal display has an effective display area 1a, a peripheral BM portion and a seal portion 1b. The display element 1 is basically the same as FIGS. 5 and 6,
The same components as those in FIGS. 5 and 6 are denoted by the same reference numerals, and detailed description is omitted. Reference numeral 12 denotes a scanning electrode driving circuit element formed of a third glass substrate on which a driving circuit having a TFT configuration is formed, and is mounted on the first glass substrate 2 of the liquid crystal display element 1 as a scanning voltage applying unit. Reference numeral 13 denotes a multilayer printed wiring board for supplying a voltage, a control signal, and the like to the scan electrode drive circuit element 12.

The mounting method is the ACF method as in the case of the COG mounting of the LSI element 7 in FIG. Reference numeral 14 denotes a signal electrode driving circuit element formed of a fourth glass substrate on which a driving circuit having a TFT configuration is formed, and is mounted on the second glass substrate 3 of the liquid crystal display element 1 as a signal voltage applying means. Reference numeral 15 denotes a multilayer printed wiring board for supplying a voltage, a control signal, a data signal, and the like to the signal electrode drive circuit element 14. As the multilayer printed wiring boards 13 and 15, a multilayer printed wiring board having a flexible structure in whole or in part such as a flexible board or a rigid flexible board is more practical than a general laminated board.

FIG. 2 shows an embodiment in which the scanning electrode driving circuit element 12 and the signal electrode driving circuit element 14 are integrated into one per side.

FIG. 3 is an example in which the two blocks of the TAB implementation of FIG. 7 are combined into one according to the present invention. In FIG.
2e is a relay electrode pattern of a transparent conductive film on the first glass substrate 2 for connecting the output terminal 13a of the multilayer printed wiring board 13 and the input terminal 12a of the scan electrode drive circuit element 12, and 2f is an adjacent drive This is a relay electrode pattern made of a transparent conductive film on the first glass substrate 2 as a signal transmission connection means between circuit elements, and is connected to the drive circuit element connection terminals 12b. An output electrode 12c of the drive circuit element is connected to the connection 2d of the transparent conductive film.

The N blocks of TAB in FIG. 5 can be similarly grouped. The configuration of FIG.
The present invention can be applied to a case where a plurality of COG blocks as shown in FIG. In any case, it is clear that the degree of contraction of the lead portion of the transparent conductive film can be reduced, and the relay electrode pattern 2f is short, so that low resistance can be realized.

In this embodiment shown in FIG. 3, the relay electrode pattern 2f is used as the signal transmission connection means between the drive circuit elements. However, in some cases, if the voltage drop due to the remaining resistance is a problem, Control signal,
It can also be used as a means for supplying data signals, power supply voltage, etc., when connecting each line in a drive circuit element to the next-stage drive circuit element. In this case, the multilayer printed wiring board is reduced in size or completely eliminated. be able to.

For the scan electrode drive circuit element 12 and the signal electrode drive circuit element 14 of the third and fourth glass substrates, drive circuits are designed with a CMOS structure using, for example, low-temperature polysilicon TFT technology, and a relatively large one is used. On a glass substrate
Although it is common to manufacture a large number of devices at the same time and divide them in a later step, it is a matter of course that the devices may be manufactured in an individually divided form. The driving circuit element using this glass substrate is TF
The number of drive circuit channels and the size of any number of drive circuit channels suitable for the display size and display density can be adjusted by the TFT array manufacturing technology and array manufacturing equipment for T liquid crystal display elements. Can be optimized for display density.

FIG. 4 shows an example of a driving circuit element as a scanning voltage applying means having a TFT-CMOS structure made of low-temperature polysilicon on a glass substrate according to the present invention. As a method for forming a TFT element on a glass substrate, a method for forming a field-effect transistor using a semiconductor material such as amorphous silicon, low-temperature polysilicon, cadmium selenide, or tellurium is known. Recently, low-temperature polysilicon has been expected particularly in terms of high mobility and stability of characteristics. After amorphous silicon is formed on a non-alkali glass such as borosilicate, it is melted and crystallized by excimer laser irradiation or the like to form a polysilicon semiconductor. In a CMOS structure, p or p ions are implanted by boron or phosphorus ions.
-Ch and n-ch can be formed, and a low-temperature polysilicon TFT can be formed by providing a source electrode, a drain electrode, a gate insulating film, and a gate electrode in the same manner as a normal amorphous silicon TFT. As described above, the liquid crystal display device of the present invention can be obtained.

[0041]

As described above, the liquid crystal display device of the present invention can be easily aligned, inspected, improved in accuracy, and improved in efficiency, without deteriorating display quality such as luminance unevenness due to blocking and electrode pitch difference. And high reliability against thermal shock, and furthermore, the rationalization of the multilayer printed wiring board is achieved, and the cost, quality and productivity can be improved.

Further, as described above, a large number of drive circuit elements can be simultaneously formed on a mother glass, and at the same time, a blank portion generated at the time of manufacturing a polysilicon TFT liquid crystal display element itself can be simultaneously formed for a simple matrix. Because of this, depending on the display size, a considerable surplus material that can only be discarded as a waste scrap material may be generated, so that a great economic effect is brought about in terms of manufacturing a TFT liquid crystal display element. Note that TCP also has a great effect of not using a silicon crystal wafer.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration of a main part of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a plan view showing a configuration of a main part of a liquid crystal display device according to another embodiment of the present invention.

FIG. 3 is an enlarged view of a driving circuit element mounting part of a main part of FIG. 1;

FIG. 4 is a plan view showing one embodiment of a driving circuit element formed on a glass substrate as a scanning voltage applying unit of the present invention.

FIG. 5 is a plan view showing a configuration of a main part of a liquid crystal display device according to a conventional example.

FIG. 6 is a plan view showing a configuration of a main part of a liquid crystal display device according to another conventional example.

FIG. 7 is an enlarged view of a conventional TAB mounting drive circuit element mounting portion.

FIG. 8 is an enlarged view of a conventional COG mounting drive circuit element mounting portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal display element 1a Effective display area 1b Peripheral BM part and seal part 2 First glass substrate 2a, 3a Transparent conductive film 2b, 3b BM part and seal part 2c, 3c Lead part 2d, 3d Connection part 2e, 2f, 3e Relay electrode pattern 3 Second glass substrate 5a Copper foil pattern portion for pitch adjustment 6, 9, 11, 13, 15 Multilayer printed wiring board 11a Output end 11b Narrow portion 12 Scan electrode drive circuit element 12a Input terminal 12b Inter-element connection terminal 12c output electrode 13a output terminal 14 signal electrode drive circuit element

Claims (3)

[Claims] 1. A pair of first and second glass substrates having a plurality of vertical strip signal electrodes made of a transparent conductive film and a plurality of horizontal strip scan electrodes made of a transparent conductive film are opposed to each other. A liquid crystal display element in which a liquid crystal material is sealed in a gap between the opposed glass substrates; a signal voltage applying element connected to the signal electrode for applying a signal voltage; and a scanning voltage application connected to the scanning electrode for applying a scanning voltage. Element, and at least one of the signal voltage applying element and the scanning voltage applying element,
A liquid crystal display device comprising: a driving circuit element made of a glass material on which a driving circuit having a thin film transistor structure is formed, which is mounted on at least one peripheral portion of the first and second glass substrates of the liquid crystal display element. 2. The liquid crystal display device, wherein at least one or more drive circuit elements are arranged on at least one side of the liquid crystal display element, and a width of one drive circuit channel in the drive circuit element is determined by scanning a display area of the liquid crystal display element. Approach the size of the pitch of the electrodes or signal electrodes, so that the length of the drive circuit element is
2. The liquid crystal display device according to claim 1, wherein the length of one side of the effective display area of the liquid crystal display element has a dimension divided by the number of driving elements arranged on the one side. 3. In a configuration in which a plurality of drive circuit elements are arranged on at least one side of a liquid crystal display element, a relay electrode pattern made of a transparent conductive film around a glass substrate is provided as connection means between the drive circuit elements. The liquid crystal display device according to claim 1, wherein: