JPH0316029B2 - - Google Patents

Description

Detailed Description of the Invention <Technical Field of the Invention> The present invention relates to an image display device having a display panel, and more particularly, to an image display device having a display panel, and more specifically, a transparent substrate having a transparent conductive film and an opposing panel having switching elements arranged in a matrix. The present invention relates to an image display device in which a display medium is interposed between a substrate and a display medium.

<Technical background of the invention and its problems> Conventionally, a flat image display device has been developed that uses, for example, a liquid crystal as a display medium interposed between a pair of substrates and a thin film transistor (hereinafter abbreviated as TFT) as a switching element. and its practical application is being promoted.

FIG. 2 is a basic circuit diagram showing the main structure of such an image display device. In FIG. 2, a single pixel of the image display device consists of a TFT 1, a display electrode 2, a transparent electrode 3, and a liquid crystal 4. When displaying an image as a display panel, a gate line Gi is used as a conductive wiring to drive the TFT 1. Each source line Sj is 240
More than one book is arranged in a matrix, and the number of pixels is nearly 60,000. The gate line Gi and source line Sj extend from one end of the display panel to the other end,
Its length must be sufficiently longer than that of a general IC, and it must be formed over a wide area. Therefore, the gate line Gi and source line Sj may be disconnected or shorted.
There is a high risk of TFT defects occurring, etc.
This causes a decrease in the yield of display panels.

In order to prevent display panel disconnection defects,
Separate lines from both ends of Gi, Gi′ and source lines Sj, Sj′
There is a method of inputting the same signal for LSI, but 1
Two LSIs are required to drive one line, and as the connection pitch becomes finer, the yield decreases due to microfabrication, and the increase in the number of driving LSIs increases costs.

Normally, in order to reduce the number of driver LSIs and widen the connection pitch of gate lines Gi and source lines Sj, connection terminals are formed for odd-numbered gate lines and source lines on one side, and for even-numbered lines on the other side. A method is used in which the connection pitch is doubled and each line is driven from one side. According to such a method, if a disconnection occurs in the gate line Gi or source line Sj, the line after that point is disconnected. It has a defect that becomes a defect.

In addition, points where shorts occur at the intersections of gate lines and source lines and defective points in the TFT are separated from other pixels by burning out the nearby gate lines or source lines with a laser or the like to intentionally break them. In these cases, the result is the same as a disconnection of the gate line and source line themselves, and a line defect occurs after the disconnection point.

In display devices that mainly display moving images such as television images, line defects are very noticeable, but point defects are almost invisible. For this reason, it has been proposed to convert line defects in display panels into point defects. This structure will be explained below.

(1) The first structure will be explained with reference to FIG.

A display panel includes a first substrate 11 (e.g., a glass substrate) on which TFTs 1 and display electrodes 2 are formed in a matrix, and a second substrate (e.g., a glass substrate) on which a common electrode 3 is formed (not shown), in which liquid crystal is sealed. If the source line 13 is disconnected, a third substrate (for example, a glass substrate) 14 having a larger external shape is provided separately from the first substrate 11, and the wiring electrode 15 is formed on the third substrate 14. The first substrate 11 and the third substrate 14 are adhesively fixed together, and the output terminal e ₁ of the source driver and the terminal a ₁ of the source line 13 of the first substrate 11 are connected to establish electrical continuity. Next, the output terminal e ₁ and the terminal b ₁ of the third substrate 14 are connected, and the other terminal c ₁ on the third substrate 14 and the other terminal d ₁ of the source line 13 are connected. This causes the source signal to
It is supplied to pixels except _B1 , and a normal image is obtained by treating line defects as point defects.

The disadvantage of this structure is that the third board 14 must be placed over the first board 11, so there is no suitable connection means for connecting the terminals a ₁ - e ₁ on a mass-produced basis. and output terminal e ₁ to the flexible wiring board (hereinafter
FPC), and when connecting the output terminal e ₁ and the terminal a ₁ on the first board 11 at the same time, the connection with the third board 14 located at the bottom of the FPC is This causes inconveniences such as being unable to do so due to FPC being an obstacle.

(2) The second structure will be explained with reference to FIG.

As a means for improving the first structure shown in FIG. 3, a structure in which a printed circuit board (hereinafter referred to as PWB) is used as an auxiliary board will be described.

Figure 4a is a plan view showing the second structure, Figure 4b
shows a sectional view taken along line A-A' in Figure a.

In FIGS. 4a and 4b, 11 is the first substrate;
12 is a second substrate, 24 is a source line, 21 is a
PWB, 22 is correction wiring on PWB, 23 is
Shows FPC. The gate line and source line drivers of the first board 11 are mounted on the FPC 23.
Electrodes on FPC (not shown) and first substrate 11
A multi-terminal connection is made to the upper electrode l ₂ at the outer periphery of the first substrate 11 . After this, change PWB21 to FPC2
Place it on the top of 3 and fix it.

When a disconnection B ₂ occurs on the display panel, a source signal is supplied between terminals a ₂ and B ₂ of the source line 24, but not between terminals B ₂ and d ₂ . Connect terminal a 2 of the source line 24 to which the source signal is supplied and _{terminal b 2 on} the PWB 21, and wire 22
Line defects are removed by connecting the other terminal c ₂ and the other terminal d ₂ on the source line 24 through the line. However, in this case, FPC2
3. In order to arrange the PWB 21 on the upper part, there is a distance of 1 mm to 1.5 mm between the terminals (a ₂ , d ₂ ) on the first board 11.
This creates a step difference of mm, which is very disadvantageous when connecting using thin metal wire. In addition, even if a display defect is discovered during the test stage of the display panel, it can be connected to the FPC23 with drivers etc. mounted on it with multiple terminals.
Display defects cannot be corrected until after the PWB 21 is fixed in position. Furthermore, even if you try to reduce the area of the display device including the display area by bending the FPC 23 connected to the first substrate 11,
This has the disadvantage that it is obstructed by the area occupied by the PWB 21.

In addition to the above, the first structure requires a step of bonding the first substrate 11 and the third substrate 14,
The second structure requires a process for fixing the first substrate 11 and the PWB 21 and fixing parts, and both have drawbacks that lead to increased costs.

<Object of the Invention> The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and it is possible to easily correct defects that occur on the display panel at any time after the completion of the display panel manufacturing process, and then connect the drive circuit. An object of the present invention is to provide an image display device capable of inspecting a displayed image by simply applying a drive signal to the drive electrodes of a display panel in a test or the like before testing. a display cell consisting of a first and second substrate, a display medium interposed within the display cell and forming a display screen, and a display medium penetrating from one edge to the other edge of the display screen on the first substrate; and a display driving conductive wiring extending outside the display screen area, wherein the conductive wiring is provided on the first substrate surface along the outer periphery of the display screen. A correction wiring for correcting a defect is provided, and the correction wiring has a first connection portion connectable to one end of the conductive wiring passing through the display screen on one side with the display screen in between. and the other side has a second connection portion connectable to the other end of the conductive wiring, and correction of the signal supply path converts a line defect based on a defect in the conductive wiring into a point defect at the first and second connection portions. It is characterized in that a function is provided on the display cell surface.

<Embodiment of the Invention> Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1a is a configuration diagram of a display panel portion explaining an embodiment of the present invention, and FIG. 1b is a sectional view taken along line X-X' in FIG. 1a.

In FIGS. 1a and 1b, a first substrate 11 on which switching elements arranged in a matrix and metal wiring (source lines and gate lines) for driving the switching elements are formed; A display cell is constituted by a second substrate (glass substrate) 12 on which a counter electrode of a transparent conductive film is formed, which is smaller than the first substrate 11 and which is arranged opposite to the first substrate 11, and a field-effect nematic liquid crystal is sealed in the cell. By doing so, a display panel is manufactured in which the overlapping region of the first substrate 11 and the second substrate 12 serves as a display screen. The metal wiring and the counter electrode are connected to a drive circuit, and the liquid crystal is driven for display. That is, by selectively controlling the switching elements on and off by appropriately selecting the metal wiring extending outward from the display screen from one edge of the display screen to the other edge, the drain directly connected to the switching element is connected. The electro-optical characteristics of the liquid crystal interposed between the electrode and the counter electrode change, and a matrix display corresponding to the selection of the switching elements is performed. In this case, the display pattern is visible to the observer through the second substrate 12.

Such liquid crystal display devices are manufactured using multilayer metal wiring and insulating layers during the manufacturing process of the display panel. That is, the second substrate 1 is placed on the first substrate 11.
A source line 32 made of a first metal is extended to the outer region of the source line 2 to form a connection terminal h between the correction terminals a ₃ and d ₃ and the FPC 31 on which the source driver is mounted. Further, after forming an insulating layer 34 on the extended source line 32, a correction wiring 33 is formed using a second metal in a direction substantially perpendicular to the source line 32, and a correction wiring 33 is formed on the correction wiring 33. Connection terminals b ₃ and c ₃ that become first and second connection portions electrically connectable to the source line 32 are formed. This terminal b ₃ and c ₃
are lead-connected to the correction terminals a ₃ and d ₃ of the source line 32, and are provided between the source lines.
The correction wiring 33 is further extended on the first substrate 11 along the outer periphery of the second substrate 12 to a gate line formation region 35, and is formed substantially perpendicular to the gate line (not shown). A terminal b ₃ formed on one side of the wiring 33 and a terminal c ₃ formed on the other side are electrically connected.

That is, in this embodiment, the correction wirings 33, 33, 33, 33 are connected to the four sides of the outer periphery of the first substrate 11 in the outer region of the second substrate 12, respectively.
The sides are extended onto one of the two adjacent sides to form a connection. Note that the correction wiring 33 does not need to be formed in an annular shape on the first substrate 11, but may be formed in a U-shape.

The line width of the correction wiring 33 is approximately twice that of the source line 32 in the display area, and the line spacing is also approximately equal to the line width. Furthermore, if the insulating layer 34 is made appropriately thick, even if a defect such as a break or a short occurs in the source line 32 or the gate line (not shown), such a defect will hardly occur in the correction wiring section 33. .

After manufacturing the above display panel, an electrical test revealed that
If a defective part _B3 is found in the source line ₃₂ and a disconnection has occurred, the defective part
The source signal is being supplied normally up to B ₃ , but
No signal is supplied from the disconnection portion B ₃ to the other terminal d ₃ (B ₃ to _{d 3} ).

In this case, the terminal a ₃ at one end of the source line 32
and one terminal _b3 of the correction wiring 33, and the other terminal _c3 on the correction wiring 33 and the terminal on the source line.
By connecting d ₃ , the source signal can be connected to the disconnected part.
It is supplied to all source lines 32 except _B3 . Therefore, line defects can be removed and converted into point defects that are almost invisible on image display.

That is, in the present invention, the correction wiring 33 is formed in a substantially U-shape on the outer peripheral edge of the first substrate 11, and the correction terminal is provided on the correction wiring 33 located between the source lines. Therefore, the correction terminal on one side of the correction wiring 33 and the terminal provided on the side connected to the source driver of the source line 32 having the defect are connected, and the correction wiring 33
By connecting the correction terminal on the other side and the terminal provided on the other end side of the source line 32, line defects are removed.

Note that the metal broken line and the correction wiring 33 are made of foil, vapor deposited film, plating film, etc. of Al, Cu, Ni, Au, etc. as in the past.
It can be formed by a printed layer or the like.

With the above configuration, (1) the terminals b 3 and _{c 3} of the correction wiring are formed in the immediate vicinity of the terminals a ₃ and d ₃ on the source line 32, and both terminals a ₃
Since both ~d _{and 3} are on the same surface of the same substrate, the length of the wire connection can be made very short, on the order of several hundred μm, and furthermore, since there are no steps, the wire connection can be made easily.

(2) Terminals a ₃ and d ₃ on source line 32 and correction wiring 3
Since the terminals b ₃ and c ₃ of No. 3 are formed on the same surface and their positions can be specified in advance, it is possible to automate the connection, leading to cost reduction.

(3) If the correction wiring width and line spacing are each several tens of μm, the wiring pitch is 100 to 200 μm, and even if 10 correction wirings 33 are formed, the correction wiring area is 1.
It only increases by ~2 mm, and the display panel hardly becomes larger.

(4) Since the correction wiring 33 is formed on the first substrate 11, it is different from the third substrate 1 in FIG. 3 in the conventional example.
4 and the PWB 21 shown in FIG. 4 are no longer necessary, and the process of attaching the board and the parts (not shown) for fixing the PWB 21 are also no longer necessary, and the number of parts can be reduced, making it possible to reduce costs.

(5) Since the correction wiring 33 can be formed without increasing the normal display panel manufacturing process, it is possible to significantly reduce costs.

(6) By forming the correction wiring 33 on the display panel, defects found by electrical tests after the display panel manufacturing process is completed can be corrected at any time after the liquid crystal is injected and sealed.

(7) A display panel whose defects have been corrected according to the present invention can display an image by simply applying an image signal to the drive electrode h using a tester or the like before connecting the drive circuit, and The display panel after correction can be inspected easily.

You can obtain excellent advantages such as:

Incidentally, in the above explanation, the source line has been described, but the same can be applied to the gate line.

Furthermore, although the description has been made using a liquid crystal as a display medium and a TFT as a switching element, there is no problem in using an electrochromic material as a display medium and a MOSFET, MIM, diode, etc. as a switching element.

<Effects of the Invention> As described above, if the present invention is used, a line area where no signal is supplied, that is, a line defect, caused by a defect in the conductive wiring can be fixed to the connecting portion located on both sides of the correction wiring and the line defect. By interconnecting the connection points of the damaged wiring conductors at the outer positions on the left and right sides of the display panel and constructing a new signal supply path using correction wiring, it is possible to supply signals, and the defective parts can be fixed. Only point defects will be converted. Therefore, the yield of the display device is improved, and defects on the display panel can be easily corrected, and costs can be reduced. The number of line defects that occur in a display panel is generally on the order of a few lines or less at most, and the probability that two or more defective portions exist in one wiring conductor is extremely low. Therefore, the present invention can eliminate line defects very effectively by arranging wiring conductors with a small number of lines around the outer periphery of the display panel. In addition, it has good workability and is suitable for mass production, and its technical value is great.

[Brief explanation of the drawing]

FIG. 1a is a plan view showing the structure of a liquid crystal display panel according to an embodiment of the present invention, FIG. 1b is a sectional view taken along line X-X' in FIG. 1a, and FIG. The basic circuit diagram of a conventional image display device, FIG. 3, and FIGS. 4a and 4b are block diagrams showing the structure of a conventional display panel, respectively. 11...first substrate, 12...second substrate, 3
1...FPC, 32... Source line, 33... Correction wiring, 34... Insulating layer.

Claims (1)

[Scope of Claims] 1. A display cell consisting of first and second substrates stacked on top of each other, a display medium interposed within the display cell to constitute a display screen, and a display medium disposed on the first substrate. In the image display device, the display drive conductive wiring extends outside the display screen area by penetrating from one edge of the screen to the other edge, and the display drive conductive wiring is provided on the first substrate surface. A correction wiring for correcting defects in the conductive wiring is arranged along the outer periphery of the screen, and the correction wiring is connected to one end of the conductive wiring passing through the display screen on one side with the display screen in between. a second connection portion having a possible first connection portion and the other side of which is connectable to the other end of the conductive wiring;
A correction function for a signal supply path that converts a line defect based on a defect in the conductive wiring into a point defect is provided on the display cell surface at the first and second connection portions. Characteristic image display device. 2. The image display device according to claim 1, wherein the conductive wiring is formed in a matrix within the display screen area.