JP2953025B2 - LCD panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] An active matrix type liquid crystal display panel using two TFTs in order to provide a redundancy in the yield can detect a defective TFT by inspecting each TFT. ,
In addition, in the detection, even if the number of bus lines increases, the terminal pitch is narrowed and the contact of the probe is not troublesome, and it is arranged in a grid on one of the pair of substrates facing each other with the liquid crystal in between. Pixel electrode, a first thin film transistor (hereinafter abbreviated as TFT) and a second TFT attached to each of the pixel electrodes, and an X-direction bus line Xn and a Y-direction bus line Yn that intersect each other. (N = 1, 2, 3), the pixel electrode is connected to a drain electrode or a source electrode of a TFT, and the TFT has one of a drain electrode and a source electrode or a gate electrode connected to a bus. The TFT is commonly connected to a line Xn or a bus line Yn, and the TFT includes two bus lines Xn or buses provided with either one of a drain electrode and a source electrode or a gate electrode in parallel. It is those that are connected to respective lines Yn, 2 this parallel of the bus line Xn or bus line Yn is at both ends, X to external circuitry
It is configured to have a connection terminal portion or a Y connection terminal portion and an X test electrode or a Y test electrode bulging at the end of each other bus line.

[Industrial applications]

The present invention relates to a liquid crystal display panel, and in particular, in an active matrix type liquid crystal display panel using two TFTs in order to provide redundancy in yield, each TFT can be inspected to detect a defective TFT, In addition, the present invention relates to a liquid crystal display panel having a terminal configuration in which the terminal pitch is narrowed even when the number of bus lines is increased and the contact of a probe is not difficult even when the number of bus lines increases.

In recent years, miniaturization of electronic devices has been promoted due to the long-term progress of microelectronics. However, one of the element devices of the machine-human interface is a liquid crystal display (LCD) that uses a liquid crystal display panel.
l displays, liquid crystal displays) are attracting attention as new displays that replace large and heavy CRT displays, which are not particularly suitable for portable types.

LCDs were once evaluated as having a low operating speed, low contrast, difficult to colorize, and a complicated driving circuit, making them impractical for large panel displays. However, recent development of new liquid crystal materials and driving methods,
Innovative developments, such as improvements in liquid crystal display panel manufacturing techniques, have the potential to result in displays with display performance comparable to CRT displays.

However, in a large-sized liquid crystal display element having a large display capacity, how to reduce display defects and improve the yield is a major issue, and there is still room for study in terms of manufacturing technology.

[Conventional technology]

In a liquid crystal display panel, large molecules are moved in a viscous liquid crystal sandwiched between two glass plates to obtain a display using an optical effect such as polarization. It was generally said that LCDs using liquid crystal display panels were not suitable for fast-moving displays such as moving images because of the slow response.

However, while a new liquid crystal material called TN (Twist Nematic, twisted nematic liquid crystal) or STN (Super TN) and its driving method have been developed, TFT (Thin Film Transformer) has been developed.
The so-called active matrix method, in which istors (thin film transistors) are arranged for each pixel, has been realized, and has come into the spotlight.

However, a single liquid crystal display panel is provided with tens of thousands to hundreds of thousands of TFTs, and it is not easy to manufacture many TFTs without defects. Therefore, it has been proposed to provide a plurality of TFTs in one pixel to provide redundancy for defects.

FIG. 6 is a plan view of an example of the conventional redundant configuration, and FIG. 7 is a plan view of another example of the conventional redundant configuration.

In the figure, 1 is a pixel electrode, 2 is a TFT, 5 is a substrate, X is a bus line X, and Y is a bus line Y.

The substrate 5 is a transparent glass plate, and the pixel electrodes 1 and bus lines X and Y provided thereon are made of ITO (Indium Tin Oxide).
xide) Photo-etched film.

Although not shown, the pixel electrode 1 is provided with another substrate facing the other, and a liquid crystal is interposed therebetween to constitute one pixel.

In this case, the drain electrodes D of the two TFTs 2 are commonly connected to the pixel electrode 1. The gate electrodes G of the TFTs 2 are commonly connected to a bus line Y, and the source electrodes S are commonly connected to a bus line X.

As described above, if two TFTs 2 are provided in one pixel electrode 1, even if one TFT 2 has a defect, the pixel electrode 1 can be relieved by another TFT 2.

Incidentally, since the two TFTs 2 provided in this way are electrically equivalent to each other, it is troublesome to detect a defective TFT.

In view of this, for example, as shown in FIG. 7, a method has been proposed in which the gate electrodes G of the individual TFTs 2 are led out by separate bus lines Y, and the individual TFTs 2 are inspected from the outside to detect defective TFTs.

[Problems to be solved by the invention]

By the way, when one TFT is provided for one pixel electrode, in order to drive the TFT, only two bus lines crossed in the XY matrix are required.

However, multiple TFTs are attached to one pixel electrode,
The electrode of each TFT is pulled out through the bus line and the defect T
When testing FT from outside, the number of bus lines increases. For example, even when two TFTs are provided, the number of bus lines on at least one side of XY to be drawn is doubled. Therefore, the terminal pitch is reduced by half.

That is, the terminal pitch of, for example, 0.3 mm, which is often used in ordinary large-sized liquid crystal display panels, becomes 0.15 mm due to an increase in the number of bus lines.

On the other hand, the thickness of the probe of a prober connected to each terminal for inspection is about 100 μmφ, and the limit of the contactable pitch of a so-called multi-prober that collectively searches terminals is about 200 μm at most.

Therefore, there is a problem that tens of thousands to hundreds of thousands of TFTs cannot be collectively inspected by a multi-tip to detect a defective TFT.

Therefore, the present invention provides two pixel electrodes provided for one pixel electrode.
It is an object of the present invention to provide a liquid crystal display panel which can detect a defective TFT by individually pulling out bus lines from the electrodes of the TFT, and further has a terminal configuration in which the pitch of the terminals is not narrowed in the detection.

[Means for solving the problem]

The above-described problem is caused by a pixel electrode arranged in a grid on one of a pair of substrates facing each other with a liquid crystal interposed therebetween, and a first thin film transistor (hereinafter abbreviated as TFT) attached to each of the pixel electrodes. ), A second TFT, a bus line Xn in the X direction and a bus line Yn in the Y direction crossing each other (n = 1, 2, 3), and the pixel electrode has a drain electrode or a source electrode of the TFT. Wherein the TFT has one of a drain electrode and a source electrode or a gate electrode connected to a bus line Xn or a bus line
The TFT is connected in common to two of the bus line Xn or the bus line Yn, in which one of the drain electrode and the source electrode or the gate electrode is provided in parallel. The two parallel lines of the bus line Xn or the bus line Yn are connected at both ends to an X connection terminal portion to an external circuit or Y
The problem is solved by a liquid crystal display panel configured to have a connection terminal portion and an X test electrode or a Y test electrode bulging at the end of each other bus line.

(Operation)

Active matrix liquid crystal display panel especially TF
In order to relieve the defect of T, two TFTs per pixel electrode
When the number of bus lines is increased, the number of bus lines increases, the terminal pitch becomes narrower, and the limit of the contactable pitch of the probe is exceeded. On the other hand, in the present invention, even if the number of bus lines increases, The pitch is not narrowed.

That is, either one of the two drain or source electrode of the TFT connected to the pixel electrode, and to connect the other to X ₁ bus line.

The gate electrode of the first TFT is connected to the bus line Y ₁ intersecting the bus lines X _1, the gate electrode of the second TFT is to connect to the bus line Y ₂ parallel to the bus lines Y ₁ I have to.

Then, the vicinity of both end portions of the bus line Y ₁ and the bus line Y ₂ which run parallel are made to be Y connection terminal portion to draw the outside when implementing.

On the other hand, when inspecting TFT defects, the bus line Y ₁
And the one end of the bus line Y _2, the bus lines Y ₁ swelled at the tip of the bus line Y ₂ as the first Y inspection electrode, the other end portion, the bus lines Y ₁ bus line Y ₂ Swells at the tip of the second Y inspection electrode.

Then, of the two TFTs, the first TFT is inspected by using the first Y inspection electrode, and the second TFT is inspected by using the second Y inspection electrode. I have.

Thus, when two TFTs are provided, two bus lines are drawn out corresponding to the respective TFTs, so that the number of bus lines is doubled and the terminal pitch is halved. However, according to the present invention, the TFT inspection can be performed without narrowing the pitch, so that a batch inspection using a multi-prober can be performed, for example.

〔Example〕

FIG. 1 is a plan view of the first embodiment of the present invention, FIG. 2 is an explanatory diagram of the inspection of FIG. 1, FIG. 3 is an explanatory diagram of the mounting of FIG. 1, and FIG. 5 is a plan view of a second embodiment of the present invention, FIG.
The figure is a plan view of a third embodiment of the present invention.

In the figure, 1 is a pixel electrode, 2a is a first TFT, 2b is a second TF
T, bus line Xn is bus line in X direction, bus line Yn
Is a Y-direction bus line, 3a is a Y connection terminal, and 3b is a first Y
Test electrode, 3c is second Y test electrode, 4a is X connection terminal, 4b
Is the first X test electrode, 4c is the second X test electrode, 7 is the substrate, D
Is a drain electrode, S is a source electrode, and G is a gate electrode (n = 1, 2, 3).

The substrate 7 is a transparent glass plate on which the pixel electrodes 1 and
Bus lines such as X ₁ , X ₂ , X ₃ , Y ₁ , Y ₂ , Y ₃ , Y connection terminal 3 a, Y test electrodes 3 b, 3 c, X connection terminal 4 a, X test electrode
The conductor patterns such as 4b and 4c are made of, for example, a transparent ITO film.

The pixel electrode 1 constitutes a display pixel, and drives a liquid crystal sandwiched between another substrate (not shown) provided opposite to the substrate.

Example 1 In FIGS. 1 to 3, the pixel electrode 1 has two TFs.
T2a, either the drain electrode D and source electrode S of 2b is connected, the other is connected in common to the bus line X _1.

On the other hand, the gate electrode G of the first TFT2a is connected to the bus line Y _1, the gate electrode G of the second TFT2b bus line Y ₂
It is connected to the.

The two bus lines Y ₁ and Y ₂ run parallel to the end face of the substrate 7 and have a pattern pitch of 0.15 mm. The vicinity of both ends is a Y connection terminal 3a. Further, bulging at one end constitute a first Y test electrode 3b by bulging a bus line Y ₁ on the tip of the bus line Y _2, the bus line Y ₂ in the other end portion in the opposite to the tip of the bus line Y ₁ This constitutes the second Y inspection electrode 3c.

Therefore, the pattern pitch of the two Y test electrodes 3b and 3c is 0.3 mm, which is the total pitch of the _two bus lines Y ₁ and Y ₂ .

Two TFT2a, upon 2b of defects inspected respectively, in case of inspecting the first TFT2a, as shown in FIG. 2 (A), a voltage is applied to the bus lines X _1, first Y Check liquid crystal driving state (not shown) by applying a signal voltage to the bus line Y ₁ through an inspection electrode 3b. At this time, the second TF
Second Y test electrode 3c leading to the bus lines Y ₂ to drive the T2b
Is in a floating state.

In addition, when examining the second TFT2b, as shown in FIG. 2 (B), a voltage is applied to the bus lines X _1,
Through the second Y test electrodes 3c investigate the driving state of the liquid crystal (not shown) by applying a signal voltage to the bus line Y _2. On this occasion,
First Y test electrode 3b continuous to the bus lines Y ₁ to drive the first TFT2a is in a floating state.

Thus, since the pitches of the two Y inspection electrodes 3b and 3c are not narrow, it is possible to easily search for them with a probe at the time of inspection.

On the other hand, when mounting the liquid crystal display panel, as shown in FIG. 3, Y buses near both ends of the _two bus lines Y ₁ and Y ₂ are used.
The connection terminal 3a is drawn out.

Embodiment 2 In FIG. 4, two TFTs 2a and 2b
There are commonly connected to the bus line Y _3.

The first TFT2a is either the drain electrode D and a source electrode S connected to the pixel electrode 1 and the other is connected to the bus line X _2. Also, the second TFT2b
Is either the drain electrode D and a source electrode S connected to the pixel electrode 1 and the other is connected to the bus line X _3.

The two bus lines X ₂ and X ₃ run parallel to the end face of the substrate 7, and the X connection terminal portions 4 a are located near both ends. Then, the bus lines X ₂ constitute a first X test electrodes 4b and swelled at the tip of the bus line X _3, the bus line X ₃ swelled at the tip of the bus line X ₂ in the other end portion at one end Constitute the second X inspection electrode 4c.

Accordingly, two X-ray inspection electrodes 4b, 4c pattern pitch is adapted to the pattern pitch of the combined two bus lines X _2, X _3, two Y inspection electrodes 3b, 3c are not narrowed pitch Therefore, it is easy to search with a prober at the time of inspection.

In mounting the liquid crystal display panel, two bus lines X ₂ and X ₃ are collectively drawn out from the vicinity of both ends in the same manner as in the first embodiment.

Example: 3 In FIG. 5, two TFTs 2a and 2b
Either the drain electrode D or the source electrode S is connected. The other is, in the first TFT2a the bus line X _2, In the second TFT2b are connected to the bus line X _3.

On the other hand, the gate electrode G of the first TFT2a is connected to the bus line Y _1, the gate electrode G of the second TFT2b bus line Y ₂
It is connected to the.

That is, in the third embodiment, the first embodiment and the second embodiment are combined so that each of the two TFTs 2a and 2b can be inspected completely independently by using two bus lines and two bus lines. The configuration is as follows.

Since the Y test electrodes 3b and 3c and the X test electrodes 4b and 4c both have a pattern pitch in which _two pairs of bus lines X ₂ and X ₃ are combined with Y ₁ and Y ₂ , respectively. It is easy to collectively search the X-direction bus line and the Y-direction bus line with a probe at the time of inspection.

In mounting the liquid crystal display panel, two bus lines X ₂ and X ₃ are connected in the same manner as in the first and second embodiments.
Y ₁ and Y ₂ are collectively drawn out from the Y test electrodes 3b and 3c and the X test electrodes 4b and 4c at both ends.

The bus lines in the X direction and the bus lines in the Y direction are relative expressions, and the essence of the present invention does not change even if they are interchanged.

Further, various modifications can be made to the pattern pitch of the bus line.

〔The invention's effect〕

In repairing a defect of a TFT provided in an active matrix type liquid crystal display panel, according to the present invention, the terminal pitch does not become narrow even if the number of bus lines increases. Therefore, in order to inspect the TFT and detect the defective TFT, the terminals are brought into contact all at once with the probe of the multi-prober, and the individual
It will be easier to find a TFT.

As a result, the present invention greatly contributes to improving the efficiency of the inspection process of the active matrix type liquid crystal display panel and improving the yield.

[Brief description of the drawings]

FIG. 1 is a plan view of the first embodiment of the present invention, FIG. 2 is an explanatory diagram of the inspection of FIG. 1, FIG. 3 is an explanatory diagram of the mounting of FIG. 1, and FIG. FIG. 5 is a plan view of a third embodiment of the present invention, FIG. 6 is a plan view of an example of a conventional redundant configuration, and FIG. 7 is a plan view of a conventional redundant configuration. 11 is a plan view of another example of FIG. In the figure, 1 is a pixel electrode, 2a is a first TFT, 2b is a second TFT, 3a is a Y connection terminal, 3b is a first Y test electrode, 3c is a second Y test electrode, and 4a is an X connection terminal. parts, 4b first X test electrodes, 4c and the second X test _{electrodes, X 1, X 2, X} 3 is bus line _{X n, Y 1, Y 2} , Y 3 is bus line Y _{n, (n} = 1 2, 3) D is a drain electrode, S is a source electrode, G is a gate electrode.

Continuation of front page (56) References JP-A-62-207971 (JP, A) JP-A-63-263743 (JP, A) JP-A-63-289534 (JP, A) JP-A-1-130132 (JP) , A) (58) Field surveyed (Int.Cl. ⁶ , DB name) G02F 1/136

Claims (4)

(57) [Claims] 1. A pixel electrode (1) arranged in a grid on one of a pair of substrates opposed to each other with a liquid crystal interposed therebetween, and a first thin film transistor attached to each of the pixel electrodes (1). (Hereinafter abbreviated as TFT) (2a), a second TFT (2b), a bus line Xn in the X direction and a bus line Yn in the Y direction crossing each other (n = 1, 2, 3), The electrode (1) is connected to the drain electrode (D) or the source electrode (S) of the TFT (2a, 2b). The TFT (2a, 2b) is connected to the drain electrode (D) and the source. One of the electrodes (S) or the gate electrode (G) is commonly connected to the bus line Xn or the bus line Yn, and the TFT (2a, 2b) is connected to the drain electrode (D). Either one of the source electrodes (S) or the gate electrode (G) is connected to two It is those which are connected to the respective bus line Xn or bus line Yn, 2 this parallel of the bus line Xn or bus line Yn is
At both ends, an X connection terminal portion (4a) or a Y connection terminal portion (3a) for an external circuit and an X test electrode (4b, 4c) or a Y test electrode (3b) bulging at the tip of another bus line, respectively. , 3c), a liquid crystal display panel. Wherein said TFT (2a, 2b), the drain electrode (D) or the source electrode (S) is, which are connected in common to the bus line X _1, the TFT (2a, 2b) is , A gate electrode (G) is connected to the bus line Y ₁ and the bus line Y ₂ , respectively. The bus line Y ₁ and the bus line Y ₂ have Y connection terminal portions (3 a) at both ends. , A first Y test electrode at each end (3b)
The liquid crystal display panel according to claim 1, further comprising: a second Y inspection electrode (3c). 3. The TFT (2a, 2b) includes a gate electrode (G).
There are those that are commonly connected to the bus line Y _3, the TFT (2a, 2b), the drain electrode (D) or the source electrode (S), respectively to the bus line X ₂ and the bus line X ₃ The bus line X ₂ and the bus line X ₃ are connected at both ends to an X connection terminal (4a), and at each end to a first X test electrode (4b).
The liquid crystal display panel according to claim 1, comprising: a second X inspection electrode (4c). Wherein said first TFT (2a), a gate electrode (G) is the connected to the bus line Y _1, and the drain electrode (D) or the source electrode (S) is, the bus line are those that are connected to X _2, the second TFT (3), the gate electrode (G) is connected to the bus line Y _2, and a drain electrode (D) or the source electrode (S) but the liquid crystal display panel of claim 2 or 3 wherein said those connected to the bus line X _3.