JPH0518789Y2 - - Google Patents

Description

[Detailed explanation of the invention] "Industrial application field" This invention is a mounting technology for liquid crystal display panels mounted with TAB substrates (IC chips for driving the liquid crystal display panels are attached to small substrates by TAB). Regarding improvements.

``Prior Art'' For example, in a liquid crystal display element (hereinafter referred to as LCD) 1 used in an active liquid crystal display panel, transparent substrates 11 and 12 such as glass are provided closely facing each other, as shown in FIG. A spacer 13 is interposed at the periphery, and these transparent substrates 11 and 12
A liquid crystal 14 is sealed in between. A plurality of pixel electrodes 15 are arranged in rows and columns on the inner surface of one transparent substrate 11, and a thin film transistor 16 is formed as a switching element in contact with each pixel electrode 15, and the drain of the thin film transistor 16 is connected to the pixel electrode 15. ing. A transparent common electrode 17 is formed almost entirely on the inner surface of the other transparent substrate 12, facing the plurality of pixel electrodes 15.

As shown in FIG. 4, the substantially square pixel electrodes 15 are arranged close to each other in rows and columns on the transparent substrate 11, close to each row arrangement of the pixel electrodes 15, and connected to a gate bus _X1 along each row. , X ₂ , . . . are formed, and source buses Y ₁ , Y ₂ , . . . are formed adjacent to and along each row of pixel electrodes 15. Each of these gate buses X _i (i=1, 2,
) and the source bus Y _j (j=1, 2, . . . ), and each gate of each thin film transistor 16 is connected to the gate bus X _i at the intersection of both buses,
Each source is connected to a source bus Y _j , respectively,
Further, each drain is connected to a pixel electrode 15.

One of each of the gate bus X _i and source bus Y _j is selected and a voltage is applied between them, and only the thin film transistor 16 to which that voltage is applied becomes conductive, and is connected to the drain of the thin film transistor 16 that is conductive. By accumulating charges in the pixel electrode 15,
By applying a voltage only to the portion of the liquid crystal 14 between the pixel electrode 15 and the common electrode 17, only the portion of the pixel electrode 15 becomes optically transparent or optically opaque. will be displayed. By discharging the charge accumulated in the pixel electrode 15, the display can be erased.

As shown in FIG. 5, a gate bus drive circuit 21 and a source bus drive circuit 2 are used to drive gate buses _X1 to _Xo and source buses _Y1 to _Yn , respectively.
2 is provided. The signals to be displayed on each row of liquid crystal pixels from the source bus drive circuit 22 are T/1 for each row.
For n hours (T=1/ _F , _F is the field frequency, which is equal to the number of screens displayed per unit time, and T is its period.) Source buses Y ₁ to _{Y n}
are output all at once. In the gate bus drive circuit 21, in synchronization with the drive of the source bus by the source bus drive circuit 22, a gate bus drive signal is sequentially outputted to each gate bus _X1 to _Xo every T/n time.

The source bus drive circuit 22 and the gate bus drive circuit 21 are each divided into several partial circuits, and each of the partial circuits is implemented as an IC. The IC chip 30 is attached to a TAB (Tape) on a printed wiring board.
Automated Bonding). This board is called a TAB board. As shown in FIG. 6, a plurality of source bus (or gate bus) driving TAB substrates 31 are provided along the edge of the LCD 1.
One end is connected to an external connection electrode made by extending the above bus, and a plurality of gate buses (or source buses) are driven along an edge perpendicular to the above edge.
One end of the TAB board 32 is connected to an external connection electrode made by extending the bus. TAB board 3
The other ends of 1 and 32 are soldered to terminals of printed circuit boards 33 and 34, respectively. The plurality of TAB boards 31 and 32 are fixed by printed circuit boards 33 and 34, respectively, and various electrical signals are inputted through these boards.

The TAB board 31 consists of a copper foil pattern 41 on a rectangular polyimide film 40 as shown in FIG.
is formed, and the IC chip 30 is mounted on the copper foil pattern 41 using TAB. The copper foil pattern 41 is formed on two opposing sides of the polyimide film 40.
extended to one edge. Polyimide film 4
Windows 42 and 43 are formed by removing elongated rectangular plate surfaces along both edges of 0, and a copper foil pattern 41 bridges over the windows 42 and 43. Note that a window 44 having a size comparable to the external shape of the IC chip is also formed at the location where the IC chip 30 is mounted. The width of window 43 is window 42
It is narrower than that of , as shown in Figure 6.
The TAB substrate 31 is bent at the window 43. The window 42 connects the TAB board 31 to the printed circuit board 33
Used for soldering to terminals. At this time, it is possible to solder the copper foil pattern 41 side facing the copper foil pattern side of the printed circuit board 33 (FIG. 8A), or to solder the polyimide film 40 side facing each other. Yes (Figure 8B). The TAB board 32 only has no window 43, and the rest
It is similar to the TAB board 31 and is used when the TAB board 31 is not bent.

``The problem that the invention aims to solve'' The pitch of the electrodes that should be connected to the TAB substrate of an LCD generally varies depending on the type of display element, such as the number of buses and the size of the display element.
Therefore, the electrode pitch of the TAB board should be adjusted to match the electrode pitch of each model of LCD.
That is, each model's
Each LCD requires a dedicated TAB board,
The number of types of TAB substrates increased, which required a large amount of development costs, which was uneconomical.

This invention aims to provide an economical liquid crystal display panel that can use a common standard TAB substrate for various types of LCDs having different electrode pitches for external connection.

"Means for solving the problem" The liquid crystal display panel of this invention consists of a liquid crystal display element, a TAB (tape automated bonding) board, a printed circuit board, and a wiring FPC (flexible printed circuit). Consists of.

The above-mentioned TAB board is a small board on which a semiconductor IC chip for driving the above-mentioned liquid crystal display is mounted by TAB, the above-mentioned printed circuit board is a board on which a plurality of the above-mentioned TAB boards are mounted, and the above-mentioned wiring FPC is for connecting the external connection electrode of the liquid crystal display element and the connection terminal of the printed circuit board.

The above printed circuit board is composed of FPC, and
It can also be configured integrally with the above wiring FPC.

``Example'' This invention uses a standard TAB substrate, and the difference between its electrode pitch and the LCD electrode pitch is
For printed circuit board mounting and newly installed wiring
Adjustments are made using FPC (flexible printed circuit). As a standard TAB board, for example, the number of electrodes to be connected to the LCD is 120, and the pitch is
A 0.3mm one is used. This idea will be described below as the first
This will be explained based on the example shown in the figure. In addition, in FIG. 1, parts corresponding to those in FIG. 6 are given the same reference numerals.
Duplicate explanations will be omitted. Standard TAB board 31' and 3
2' are mounted on printed circuit boards 33 and 34, respectively, and one ends of wiring FPCs 51 and 52 are connected to the connection terminals of these printed circuit boards, respectively.
Their other ends are connected to the electrodes 53 of the LCD 1, respectively. As shown in FIG. 2, the wiring FPCs 51 and 52 are made by forming a copper foil pattern on a polyimide film 55.

For example, the following method is used to connect the wiring FPCs 51 and 52 and the LCD electrode 53. In the first method, the LCD electrodes 53 are metallized by plating or other means, and nickel, gold, etc. are laminated thereon, and the terminals 55 of the FPCs 51 and 52 for wiring are solder-plated to form these LCD electrodes. to 53
This is a method in which the FPC terminals 55 are stacked one on top of the other and heated and soldered using means such as a laser.

The second method is to connect the LCD electrode 53 and FPC terminal 55
As shown in FIG. 2, an anisotropic conductive film 56 is placed between
This is a method of bonding by applying heat and pressure to the adhesive. In the anisotropic conductive film 56, fine metal particles 57 of several microns are arranged at equal intervals on an adhesive base material, and the conductive film 56 is crushed by heat and pressure.
The LCD electrode 53 and the FPC terminal 55 are metal particles 57
At the same time, the surrounding adhesive layer is melted by the heat, and the transparent substrate 11 of the LCD and the wiring FPCs 51 and 52 are bonded together (the second
Figure B). In addition, when using the second method, the LCD
The electrode 53 does not need to be metallized. on the other hand,
It is desirable that the FPC terminal 55 be plated with gold.

When connecting the wiring FPCs 51 and 52 to the printed circuit boards 33 and 34, respectively, it may be performed according to the first and second methods described above. Also, standard TAB
A method similar to the first or second method described above is also used when mounting the substrates 31' and 32' on the printed circuit boards 33 and 34, respectively.

The pitch of the terminals 55 at one end of the wiring FPCs 51 and 52 is equal to the pitch of the LCD electrode 53 to be connected, and the pitch of the terminals at the other end of the wiring FPC is equal to the pitch of the terminals of the printed circuit board 33 or 34. Set. Pitch and standard of LCD electrode 53
The difference in electrode pitch between the TAB boards 31' and 32' may be adjusted by the copper foil patterns of the printed circuit boards 33 and 34, or by the copper foil patterns of the wiring FPCs 51 and 52. Or both can be used together.

Since the FPC for wiring can be bent freely as needed, there is no need to provide a special bending window on the TAB board as in the past. Standard TAB
The substrates 31', 32' can be mounted on either the front or back surface of the printed circuit boards 33, 34, or both.

In the explanation so far, it has been assumed that the LCD is an active LCD, but this invention need not be limited to that case, and it is clear that it can be applied to passive LCDs as well.

Other Embodiments In FIG. 1, the printed circuit boards 33 and 34 may not be used and FPCs 51 and 52 may be used instead.
In that case, the dimensions of the FPC are increased by the size of the printed circuit board, and a standard TAB board 31' or 32' is mounted thereon.

``Effect of the invention'' According to this invention, a common standard TAB can be used for various types of LCDs with different electrode pitches using a printed circuit board for TAB board mounting and an FPC for wiring.
It is no longer necessary to prepare a dedicated TAB board for each type of LCD, as was the case in the past, and a large amount of development costs can be saved.

Since the FPC can be bent freely at almost any curvature and angle as necessary, the degree of freedom in mounting when configuring an LCD display device is expanded.

[Brief explanation of the drawing]

Figures 1A and B are a perspective view and a side view of the main parts, respectively, to show an embodiment of this invention, and Figure 2 is the liquid crystal display element (LCD) 1 and wiring FPC 5 of Figure 1.
1 and 52 using an anisotropic conductive film; FIG. 3 is a cross-sectional view of essential parts showing an example of a liquid crystal display element; FIG. Figure 5 is a block system diagram of a liquid crystal display panel using the liquid crystal display element shown in Figure 3. Figure 6 is a perspective view of a conventional liquid crystal display panel equipped with a dedicated TAB board. , FIGS. 7A and 7B are respectively a perspective view and a sectional view of the TAB board 31 in FIG. It is a diagram.

Claims (1)

[Scope of claim for utility model registration] (1) A liquid crystal display panel consisting of a liquid crystal display element, a TAB (tape automated bonding) board, a printed circuit board, and a wiring FPC (flexible printed circuit). The above-mentioned TAB board is a small board mounted with a semiconductor IC chip for driving the above-mentioned liquid crystal display element using a TAB, and the above-mentioned printed circuit board is a board on which a plurality of the above-mentioned TAB boards are mounted. The wiring FPC is a liquid crystal display panel that connects the external connection electrodes of the liquid crystal display element and the connection terminals of the printed circuit board. (2) The liquid crystal display panel according to claim (1), wherein the printed circuit board is formed of an FPC, and is formed integrally with the wiring FPC.