JPS61294414A - Matrix terminal type liquid crystal display device - Google Patents

Abstract

PURPOSE:To decrease the number of terminals by forming the respective terminals connected to picture elements into a matrix by the intervention of two-terminal elements formed on the same substrate as the substrate for the respective terminals thereby decreasing the number of the terminals to be connected to an external driving circuit. CONSTITUTION:This device is a kind of a decoder which forms picture element line electrode terminals 6 drawn out of the respective picture element line electrodes into the matrix by the intervention of the peripheral two-terminal elements 28 and converts the same to the terminal line electrodes 7 and the terminal row electrodes 8. If the terminals 6 are N-pieces, the respective numbers of the terminal line electrodes and terminal row electrodes are N<1/2> pieces and the totaled 2(N<1/2>) pieces are connected to the external driving part 4. If N<1/2> is not integer, the integer larger than N<1/2> and nearest the same is the number of the terminal line and row electrodes. It is not necessary that the numbers of the terminal line and row electrodes are the same. These numbers are multiplied so that the number is made equal to or larger than the number of the picture element line electrode terminals. The number of the terminal connection points and the ICs for driving is thereby considerably decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display device with a large display capacity used in information terminals, personal computers, and the like.

[Conventional technology]

In recent years, applications of liquid crystal display devices (LCDs), mainly twisted nematic type devices, have been developed and are being used in large quantities in the fields of wristwatches and calculators. In addition, in recent years, letters, figures,
Matrix LCDs are also used that can display arbitrary displays such as . In order to expand the field of application of this matrix type LCD, it is necessary to increase the display capacity.

In conventional LCDs, the voltage-transmittance change characteristic does not have a very steep rise, so crosstalk 1 is likely to occur, and the number of scan lines is limited to about 100 lines in terms of contrast and viewing angle. In order to significantly improve this limitation, active matrix LCDs have recently been devised in which a switching element is arranged in each pixel of the LCD. Switching elements include thin film transistor elements (TPT) made of amorphous silicon (A-81), polysilicon (poly-81), t-semiconductor materials, and nonlinear resistors such as metal-insulator-metal elements (hereinafter abbreviated as MIM). There is an element.

FIG. 2 shows a basic circuit diagram of an LCD using these devices.

In FIG. 2(a), the nonlinear resistance element 11 is connected to the liquid crystal pixel 10.
are connected in series with pixel row electrode 12 and pixel column electrode 1.
This is the circuit connected to 3. (b) shows an example in which f-) of the thin film transistor element 14 is connected to the pixel row electrode 12, the source is connected to the pixel column electrode 13, and the drain is connected to the liquid crystal pixel 10. Note that the other side of the liquid crystal pixel 10 becomes a counter electrode. For details, see Takahashi et al., “Liquid Crystal Display Device Using Nonlinear Active Elements,” Chassis Technical Report, Volume 24, Page 19 (19
[Problems to be Solved by the Invention] However, as the display capacity increases using this method, the number of terminals also increases accordingly. A4 required in the future
LCD with about 1000 x 100 pixels, about the size of a printing plate
In addition to making it difficult to connect terminals, the number of peripheral driving ICs also increases, which in turn increases the volume occupied by peripheral circuit-related components and increases costs.

As a method to eliminate such drawbacks, a method has been proposed in the past in which peripheral drive I (4-TFTs are formed and stacked on the LCD substrate, and a prototype using poly-8i TFTs has been announced. -8iTFT requires the use of a quartz substrate due to the element manufacturing temperature, and the manufacturing equipment is also difficult to accommodate larger substrate areas, making it difficult to increase the area and reduce costs. It is expected that the yield will be low because the functions of the silicon IC are directly converted into TFTs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a matrix/diss terminal type liquid crystal display device which eliminates such conventional drawbacks and reduces the number of terminals connected to an external drive circuit.

[Means for solving problems]

The present invention provides an active matrix liquid crystal display device having a large number of terminals, in which each terminal t5 connected to each pixel and a two-terminal element formed on the same substrate are used to form a matrix and a matrix, and are connected to an external drive circuit. In the present invention, a two-terminal element is a matrix terminal type liquid crystal display device characterized by a reduction in the number of terminals to be connected.
Typically, it refers to a capacitor element or a resistor element, to distinguish it from the non-linear resistor element connected to each liquid crystal pixel as shown in Figure 2 (0) (b), and to use it to form a matrix of terminals. This two-terminal element is hereinafter referred to as a peripheral two-terminal element.

Furthermore, an active matrix liquid crystal display device refers to a second
As shown in Figures 1) and 2), an LCD is referred to as an LCD in which a switching element is arranged in series in each liquid crystal pixel.

A circuit example of a liquid crystal display device obtained by the present invention is shown in FIG. 1, and the present invention will be described in detail below based on FIG.

The present invention includes a display section 1, a row decoder section 2, a column decoder section 3,
It is composed of a driving section 4. The display section 1 is a conventional twist
A simple matrix or square LCD using a Nemati (TN) type liquid crystal may be used, but from the viewpoint of display capacity and contrast, an active type LCD with each pixel 5 having the circuit configuration shown in Fig. 2 (a) and (b) is suitable. A multi-screen LCD is preferable.

The row decoder section and the column decoder section are the main parts of the invention. In the former case, as shown in FIG. 1, the pixel row electrode terminal 6 from which each pixel row electrode is drawn out is connected to the terminal row electrode 7 and the terminal column electrode 8 by IJ hooking via the peripheral two-terminal element 28. It is a kind of decoder that converts. When there are N pixel row electrode terminals 6, the number of terminal row electrodes and terminal column electrodes is f, and a total of 26 are connected to the external drive unit 4.
connected to. If 〆T is not an integer, the number of terminal row and column electrodes is an integer larger than 〆W and closest to it. Also, the numbers of terminal row and column electrodes do not need to be the same, and these ? multiplied by the number of pixel row electrode terminals,
Or even more.

The latter column decoder section also has basically the same configuration as the row decoder section.

A terminal row electrode and a terminal column electrode of the row decoder section and the column decoder section are connected to a driving section. The drive unit is usually 1
It is composed of one or several integrated circuit elements (ICs).

A method for driving the matrix-diss terminal type liquid crystal display device of the present invention will be described below.

The voltage waveforms applied to the pixel row electrode terminals 6 and pixel column electrode terminals 9 of the display section are basically the same as those of a normal simple matrix, box type, or active matrix type LCD. Also, in order to generate such a voltage waveform, the terminal row electrode 8 is
and sets the voltage waveform to be applied to the terminal row electrode 7. Here, the relationship between the voltage applied to the terminal row/column electrode 8.7 K and the voltage applied to the pixel row or column electrode terminal 6.9 is as follows, regardless of whether the two-terminal element is a capacitor element or a resistor element. The relationship between the IJ Fuchs row/column terminal voltage and the voltage applied to the liquid crystal is the same. Therefore, the voltage averaging driving method is also used in the display device of the present invention.

〔Example〕

The present invention will be described in detail below based on an example. (Example 1) This example is applied to an active matrix type LCD using a metal-insulator-metal (MIM) element consonant, which is a type of nonlinear resistance element. , a capacitor element is used as the zero-periphery two-terminal element 28, which is an example to which the present invention is applied. A cross-sectional view of a typical example of an MIM element and a liquid crystal pixel is shown in FIG. A cross-sectional view of a typical example of a capacitor element of a decoder is shown in FIG.

First, the process of forming a film on the lower glass substrate 19 will be explained.

In FIG. 3, in the fourth prisoner, first the lower glass substrate 19
t Cover with a protective layer 18 such as TjL205, 5i02.

Although this protective layer 18 prevents sodium ions and the like from entering from the glass, it is not essential and can be omitted. Tantalum (Ta) on top of this! Ordinary argon (A
r) Inside, form 40001 with DC Suno 4 ivy. A pattern was formed by photolithography using ordinary dry etching to form a pixel row electrode 12 and a peripheral lower electrode 21. After coating with the resist, an insulating layer 14 made of 500X tantalum pentoxide (Ta203) is formed on the pixel row electrode 12 and the peripheral lower electrode 21 is anodized in 0.1 vt% citric acid. , Ta of 20001
205 dielectrics 22 were formed.

The upper electrode 15 and the peripheral upper electrode 23 were made of chromium (Cr), and after film formation by a normal vacuum evaporation method, they were formed into four-turn layers using IJ Sogtufi. The pixel electrode material 6 was a transparent electrode made of indium oxide-tin oxide (ITO), which was formed into a film by magnetron sputtering, and patterned by ordinary photophosphorography.

Film formation and patterning on the upper glass substrate 20 are almost the same as those on the lower glass substrate. However, Ta and T
A205 is used only for forming the capacitor element in the decoder, and does not form the MIM element. Further, the pixel column electrodes 13 are made of ITO and are formed in a stripe shape like a normal simple multiplex.

By the above manufacturing method, 400 pixel row electrodes 12 and 4
00 pixel column electrodes 13 are formed, and the pixel pitch is 0.3.
A display section of 400×400 pixels was formed. As shown in FIG. 1, capacitor elements, row and column decoders were formed, and the number of terminals and column electrodes was 20 each. That is, according to the present invention, the number of external terminals was reduced by one digit from 800 to 80. As a result, the number of drive ICs was reduced from 20 to 2, resulting in a significant cost reduction.

These upper and lower glass substrates are used as a normal TN type LCD.
Stretch and seal together using the method used in TN
An LCD according to the present invention was completed by injecting a type liquid crystal (manufactured by Merck, ZLI-1565) and attaching a polarizing plate.

Cell thickness is 8μm1 Polarizing plate is NPF-110 manufactured by Nitto Denko
It is 0H.

The LCD according to this embodiment is 1/? ) When driven using the bias voltage averaging method, the contrast ratio was 5:1, the viewing angle was as wide as ±50°, and the display characteristics were almost the same as those of the static display.

In this embodiment, the MIM is formed on the pixel row electrode side, but an LCD having the same function as this embodiment can also be realized by forming the MIM on the pixel column electrode side.

Further, in this embodiment, decoders are provided for both the pixel row electrode terminal and the pixel column electrode terminal to form a matrix, but it is not possible to form a matrix for only one of them.
This alone reduces the number of terminals by nearly half.

(Example 2) In this example, all of the peripheral two-terminal elements were manufactured using the same manufacturing method as in the example, except that the water type capacitor element shown in Figure 4 was replaced with the water type resistor element shown in Figure 5. did. Thin film resistor 24 is T1 or tantalum nitride (TaN). The former film was formed by DC sputtering of Ta in argon, and the latter film was formed in argon containing some nitrogen. The arm turning was done by photolithography using dry etching.

Further, in order to adjust the resistance value, a meandering pattern or the like was used for the thin film resistor 24 as appropriate.

Similarly to Example 1, the LCD according to the present example also had display performance comparable to that obtained when statically driven.

(Example 3) This example is an example in which the present invention is applied to an active Q matrix LCD using a-81TPT. - A capacitor element was used as a peripheral two-terminal element. A cross-sectional view of a typical example of a TPT element and a liquid crystal pixel is shown in FIG. 6.A cross-sectional view of a typical example of a capacitor element of a decoder is already shown in FIG. In this embodiment, both the row and column decoders are formed on the lower glass substrate side. 1 Mu is basically the same as in Example 1. Components that are the same as those in FIGS. 3 and 4 will be described using the same numbers.

In this example, first, tantalum was deposited by DC sputtering.
It was formed on the protective layer 18. It was patterned by dry etching and used as the pixel row electrode 12 and the peripheral lower electrode of the capacitor. By anodizing these, 20
00X Ta205 was formed to serve as the gate insulating layer 25 and dielectric. After this, a-
81 layers 26 were formed, and pixel column electrodes and connection electrodes 27 were formed of metal such as Cr. or.

At the same time, the upper peripheral electrode of the decoder portion was also formed of Cr.

After that, a pixel electrode was formed using ITO.

The counter electrode 15 made of ITO was simply attached all over the upper glass substrate 20 and the protective layer 18.

By combining these two substrates and using the same method as in Example 1), a TN type LCD was manufactured. By driving this in the same manner as in Example 1, display characteristics comparable to those obtained with static driving were obtained.

(Example 4) This example is all in Example 1 except that the peripheral two-terminal element was replaced with a MIM element shown in FIG. 3 from a capacitor element.
Similarly to Example 1, the LCD according to this Example, which was manufactured as a prototype using the same manufacturing method as in Example 1, had a display performance comparable to that in static driving.

〔Effect of the invention〕

As explained above, according to the present invention, the number of terminals taken out to the outside from a large display capacity liquid crystal display device is reduced by about one order of magnitude, and the number of terminal connection points and the number of driving ICs are greatly reduced. This has the effect of greatly contributing to cost reduction and downsizing of the device.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of a matrix terminal type liquid crystal display device according to the present invention, FIGS. 2(a) and 2(b) are circuit diagrams of one pixel of an active ψ matrix type LCD, and FIG. FIG. 4 is a cross-sectional view of the structure of one pixel in Examples 1 and 2, and FIG. 5 is a cross-sectional view of the structure of a two-terminal device around Examples 1 and 30.
FIG. 6 is a cross-sectional view of the structure of the peripheral two-terminal element of Example 2, and FIG. 6 is a cross-sectional view of the structure of one pixel of Example 3. DESCRIPTION OF SYMBOLS 1... Display part, 2... Row decoder part, 3... Column decoder part, 4... Drive part, 5... Pixel, 6... Pixel row electrode terminal, 7... Terminal Row electrode, 8... Terminal column electrode, 9... Pixel column electrode terminal, 10... Liquid crystal pixel, 1
DESCRIPTION OF SYMBOLS 1... Nonlinear resistance element, 12... Pixel row electrode, 13
... Pixel column electrode, 14... Thin film transistor element,
15... Counter electrode (upper electrode) 16... Pixel electrode,
17... Liquid crystal layer, 18... Pixel column electrode, 19...
Lower 1 part glass substrate, 20... Upper glass substrate, 21.
... Lower peripheral electrode, 22... Dielectric, 23... Upper peripheral electrode, 24... Thin film resistor, 25...? -) Insulating layer, 26...d-81 layer, 27... Connection electrode, 2
8... Peripheral two-terminal element. Figure 1 Horse Figure 2 Horse Figure 3 Figure 5

Claims (1)

[Claims] (1) In an active matrix liquid crystal display device having a large number of terminals, each terminal connected to each pixel is
1. A matrix terminal type liquid crystal display device, characterized in that the number of terminals connected to an external drive circuit is reduced by forming a matrix through two terminal elements formed on the same substrate as each terminal.