JP2552368B2 - Active matrix display - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a display device that performs display by applying a drive signal to a display pixel electrode via a switching element, and in particular, the pixel electrodes are arranged in a matrix. The present invention relates to an active matrix drive type display device which is arranged in a matrix to perform high density display.

(Prior Art) Conventionally, in a liquid crystal display device, an EL display device, a plasma display device, etc., a display pattern is formed on a screen by selectively driving picture element electrodes arranged in a matrix. There is. A voltage is applied between the selected pixel electrode and a counter electrode facing the pixel electrode, and the display medium interposed therebetween is optically modulated. This light modulation is visually recognized as a display pattern. As a driving method of the picture element electrodes, an active matrix driving method is known in which individual picture element electrodes are arranged and a switching element is connected to each of the picture element electrodes for driving. As a switching element for selectively driving the pixel electrode, a TFT (thin film transistor) element, a MIM (metal-insulating layer-metal) element, a MOS transistor element, a diode, a varistor, etc. are generally known. The active matrix drive system is capable of high-contrast display, and has been put to practical use in liquid crystal televisions, word processors, terminal display devices of computers, and the like.

(Problems to be Solved by the Invention) When high-density display is performed using such a display device, it is necessary to arrange a large number of pixel electrodes and switching elements. However, the switching element may be formed as a malfunctioning element when it is formed on the substrate. A pixel electrode connected to such a defective element causes a pixel defect that does not contribute to display.

A structure for correcting a picture element defect is disclosed in, for example, Japanese Patent Laid-Open No. 61-15.
It is disclosed in Japanese Patent No. 3619. In this structure, a plurality of switching elements are provided for each picture element electrode. One of the plurality of switching elements is connected to the pixel electrode, and the other is not connected to the pixel electrode. If the switching element connected to the pixel electrode is defective, laser trimmer,
The switching element is separated from the picture element electrode by a tuning cutter or the like, and another switching element is connected to the picture element electrode. The connection between the switching element and the pixel electrode is performed by attaching a minute conductor with a dispenser or the like, or by coating a predetermined portion with Au, Al or the like on the substrate. Furthermore, JP-A-61-56382 and JP-A-5959
Japanese Unexamined Patent Publication No. -101693 discloses a structure in which metal layers are electrically connected to each other by irradiating a laser beam to melt a metal.

The above defect repair must be performed in the state of the active matrix substrate before assembling the display device.
The reason is that after the display device is completed, a part of the metal evaporated or melted by the laser light irradiation is mixed in the display medium such as liquid crystal present between the pixel electrode and the counter electrode, and the display medium This significantly deteriorates the optical characteristics of. Therefore, any of the conventional pixel defect corrections described above is applied in the active matrix substrate manufacturing process before the display device is assembled, that is, before the display medium is enclosed.

However, it is extremely difficult to detect a pixel defect at the manufacturing stage of the active matrix substrate. Especially in large-sized display devices with 100,000 to 500,000 or more picture elements, use extremely high-precision measuring equipment to detect defective switching elements by detecting the electrical characteristics of all picture element electrodes. Must. For this reason, the inspection process becomes complicated, and mass productivity is hindered. Therefore, the cost is increased. For this reason, in a large-sized display device having a large number of picture elements, the picture element defect cannot be corrected in the state of the substrate using the laser light described above.

An active matrix display device capable of correcting a pixel defect using laser light in a display device state is disclosed in Japanese Patent Application No. 1-11.
6694. FIG. 1A shows a plan view of an active matrix substrate used in an improved example of such a display device. Assemble the display device using the substrate of FIG.
The cross-sectional structure of this display device taken along the line B-B and the line C-C in the figure is shown in FIGS. 3 and 4. A base coat film 2 is formed on a glass substrate 1, and gate bus lines 3 and source bus lines 4 are arranged in a grid pattern on the base coat film 2. In a rectangular area surrounded by the gate bus wiring 3 and the source bus wiring 4, picture element electrodes 5 made of a transparent conductive film (ITO) are provided to form a picture element pattern in a matrix.

A TFT 6 is arranged near the corner of the picture element electrode 5, and the TFT 6 and the picture element electrode 5 are electrically connected by a drain electrode 16. A spare TFT 7 is arranged near the other corner of the picture element electrode 5, and the spare TFT 7 and the picture element electrode 5 are electrically connected by a drain electrode 16a. The TFT 6 and the spare TFT 7 are arranged side by side on the gate bus wiring 3, and the source electrode 15 of the TFT 6 and the source bus wiring 4 are connected by a branch wiring 8. Reserve
The source electrode 15a of the TFT7 is the source electrode extension end 8a,
It is led to the connecting portion 25. At the connecting portion 25, the source electrode extension end 8a
Are opposed to the branch wiring 8 in a non-conducting state. Therefore,
Of the two TFTs 6 and 7, only TFT6 is the source bus wiring 4
, And the spare TFT 7 is not connected to the source bus line 4.

The cross-sectional structure near the TFT6 will be described with reference to FIG. still,
The configuration of the spare TFT7 is the same as that of the TFT6. Gate bus wiring 3
Insulating film on the gate electrode 9 formed as a part of
10 are formed. From above, a base insulating film 11 which also functions as a gate insulating film is deposited over the entire surface of the substrate. An amorphous silicon (a-Si) intrinsic semiconductor layer 12 and a semiconductor layer protective film 13 for protecting the upper surface of the intrinsic semiconductor layer 12 are sequentially laminated on the base insulating film 11. Furthermore, n-type semiconductor layers 14 and 14 made of a-Si are stacked on top of this. A source electrode 15 and a drain electrode 16 are formed on the n-type semiconductor layers 14 and 14, respectively. The semiconductor layer protection film 13 functions as an etching stopper when the source electrode and the drain electrode are patterned by etching.

The pixel electrode 5 is patterned on the base insulating film 11. A protective film 17 and an alignment layer 19 are deposited on the entire surface of the substrate so as to cover the upper surfaces of the TFT 6 and the pixel electrode 5.

As shown in FIG. 4, at the connecting portion 25, the base coat film 2 is formed.
The joint metal layer 24 is formed thereon. The base insulating film 11 described above is deposited on the joint metal layer 24. On the base insulating film 11, the source electrode extension end 8a connected to the source electrode 15 of the spare TFT and the branch wiring 8 connected to the source bus wiring 4 are placed. The source electrode extension end 8a and the branch wiring 8 are separated from each other and maintain a non-conductive state. Therefore, the spare TFT 7 is not electrically connected to the source bus line 4. The source electrode extension end 8a and the branch wiring 8 are completely covered with a protective film 17. The protective film 17 is provided to electrically connect the branch wiring 8 and the source electrode extension end 8a in a state of being separated from the liquid crystal layer 18 which is a display medium.

A color filter 21 is formed on the inner surface of the other glass substrate 20 facing the glass substrate 1. The counter electrode 22 and the alignment layer 23 are formed on the entire surface of the color filter 21 in an overlapping manner. A liquid crystal layer 18 is enclosed as a display medium between the pair of glass substrates 1 and 20.

All pixel electrodes 5 of the liquid crystal display device having such a configuration
Then, a drive voltage is applied via TFT6. In this manner, when the display device is entirely driven, the pixel defects can be easily visually recognized. If a pixel defect due to a defect in the TFT 6 has occurred, it can be easily repaired by using the connection portion 25. That is, energy such as laser light is externally applied to the overlapping portion of the joint metal layer 24, the branch wiring 8 and the source electrode extension end 8a through the lower glass substrate 1. In the overlapping portion of the branch wiring 8 and the joint metal layer 24, when the laser light is irradiated, dielectric breakdown of the base insulating film 11 occurs, and the branch wiring 8 and the joint metal layer 24.
24 and 24 are fused and connected to each other to be in a conductive state. Similarly,
Even in the overlapping portion of the source electrode extension end 8a and the joint metal layer 24,
Dielectric breakdown of the base insulating film 11 occurred and the source electrode extension end
8a and the joint metal layer 24 are fused and connected to each other to be in a conductive state. In this way, the branch line 8 and the source electrode extension end 8a are electrically connected via the joint metal layer 24, and the spare TFT 7 is driven by the source bus line 4.

When it is necessary to separate the TFT 6 from the pixel electrode 5 due to poor insulation of the TFT 6, the drain electrode 16 of the TFT 6 is irradiated with laser light and cut. By separating the TFT6 and the picture element electrode 5, the picture element electrode 5 is a preliminary TF.
Driven normally by T7.

In this display device, since the protective film 17 is formed above the connection portion 25, the above-described connection by laser light irradiation is performed between the substrate 1 and the protective film 17. Therefore, the metal melted by the laser irradiation is not mixed into the display medium. However, laser light stability, reproducibility, joint metal layer 2
4, base insulating film 11, branch wiring 8, source electrode extension end 8a,
The protective film 17 may be destroyed depending on the material, shape, etc. of the protective film 17. When the protective film 17 is destroyed, the metal melted by laser light irradiation is the liquid crystal layer 18 serving as the display medium.
May be mixed with the counter electrode 22 and contact the counter electrode 22. When such contact occurs, the source bus line 4 and the counter electrode
There will be a leak with 22. Due to such a leak, the pixel defect cannot be reliably corrected by laser light irradiation.

The present invention has been made to solve such a problem. That is, it is an object of the present invention to provide an active matrix display device capable of surely correcting a pixel defect due to a switching element failure in a state of the display device in which the generation position of the pixel defect can be easily specified.

(Means for Solving the Problem) In an active matrix display device of the present invention, a pair of opposed substrates, at least one of which has a light-transmitting property, and optical characteristics modulated in response to an applied voltage which is inserted between the substrates. A display medium, a picture element electrode arranged in a matrix on the inner surface of one of the pair of substrates, a switching element and a preliminary switching element electrically connected to the picture element electrode, A scanning line connected to the switching element and the preliminary switching element; a signal line connected to the switching element; and a counter electrode formed on an inner surface of the substrate facing the one substrate, A connection portion is formed in which the extended end of the signal input terminal of the pre-switching element and the branch wiring branched from the signal line are in close proximity to each other in a non-conductive state via at least an insulating film. When the pendant element is defective, the connection portion is irradiated with light energy to electrically connect the extended end of the signal input terminal of the preliminary switching element and the branch wiring. In order to prevent the occurrence of defects during irradiation of light energy, the counter electrode is formed in a portion other than the portion facing the connection portion, and the switching element, the preliminary switching element, the signal line and the scanning line are formed. A protective film is formed so as to cover at least the cover, and thereby the above-mentioned object is achieved.

(Operation) If the active matrix display device having the above structure is driven over the entire surface, the position where the pixel defect occurs can be easily confirmed. By driving all the pixel electrodes, the corresponding display medium causes optical modulation in accordance with the driving voltage. However, when the switching element is defective, this optical modulation does not occur and it is visually recognized as a pixel defect. This pixel defect can be easily identified by using a magnifying lens even in a display device in which hundreds of thousands of minute pixel electrodes are arranged.

When the generation position of the pixel defect is confirmed, optical energy such as laser light is irradiated to the connection portion from the outside through the transparent substrate. At the connection portion, the extended end of the signal input terminal of the preliminary switching element and the branch wiring branched from the signal line are electrically connected to each other by laser light irradiation. In this way, the spare TFT 7 and the signal line are electrically connected via the connecting portion. Further, if necessary, a defective switching element connected to the pixel electrode can be cut by irradiation with light energy to be separated from the pixel electrode.

When the connection is made by irradiation with the light energy, the metal forming the extended end of the signal input terminal and the branch wiring is melted. The molten metal may be mixed in the display medium and further contact the counter substrate side. When such contact occurs,
It causes pixel defects. However, in the active matrix display device of the present invention, the counter electrode on the counter substrate is formed in a portion other than the portion facing the connection portion. Therefore, even when molten metal or the like is mixed in the display medium, it does not come into contact with the counter electrode. Therefore, the configuration of the present invention can surely correct the pixel defect.

(Examples) The present invention will be described below with reference to Examples. FIG. 1A shows an active matrix substrate used in an embodiment of the display device of the present invention. In this embodiment, an active matrix substrate similar to that described in the above-mentioned improved example is used. FIGS. 1B and 1C show the configuration of each section along the line BB and the line CC of this embodiment using the substrate of FIG. 1A. A base coat film 2 made of Ta ₂ O ₅ , Al ₂ O ₃ , Si ₃ N ₄ or the like is formed on a glass substrate 1 with a thickness of 3000 Å to 9000 Å. The base coat film 2 does not necessarily have to be provided,
May be abolished. Gate bus lines 3 for supplying scanning signals and source bus lines 4 for supplying data signals are arranged in a grid pattern on the base coat film 2. The gate bus wiring 3 is generally formed of a single layer of Ta, Al, Ti, Ni, Mo or the like or a multilayer metal thereof, but Ta is used in this embodiment. The source bus line 4 is also made of the same metal, but Ti is used in this embodiment. A base insulating film 11 formed on the entire surface of the substrate is interposed at the intersection of the gate bus wiring 3 and the source bus wiring 4.

A pixel electrode 5 made of a transparent conductive film (ITO) is formed in a rectangular area surrounded by the gate bus wiring 3 and the source bus wiring 4.
Are provided to form a matrix-shaped picture element pattern. A TFT 6 is arranged near the corner of the picture element electrode 5, and the TFT 6 and the picture element electrode 5 are electrically connected by a drain electrode 16. A spare TFT 7 is arranged near the other corner of the picture element electrode 5, and the spare TFT 7 and the picture element electrode 5 are electrically connected by a drain electrode 16a. The TFT 6 and the spare TFT 7 are arranged side by side on the gate bus wiring 3, and the source electrode 15 of the TFT 6 and the source bus wiring 4 are connected by a branch wiring 8.
The source electrode 15a of the spare TFT 7 is guided to the connecting portion 25 by the source electrode extension end 8a. In the connecting portion 25, the source electrode extension end 8a is placed opposite to the branch wiring 8 in a non-conducting state. Therefore, of the two TFTs 6 and 7, only the TFT 6 is electrically connected to the source bus line 4, and the spare TFT 7 is the source bus line 4.
Not connected to. Details of the cross-sectional structure of the connecting portion 25 will be described later.

The cross-sectional structure near the TFT 6 will be described with reference to FIG. 1B. still,
The configuration of the spare TFT7 is the same as that of the TFT6. Gate bus wiring 3
A gate insulating film 10 made of Ta ₂ O ₃ obtained by anodizing the surface of the gate electrode 9 is formed on the Ta gate electrode 9 formed as a part of. From above, a base insulating film 11 of SiN _x (for example, Si ₃ N ₄ ) that also functions as a gate insulating film is deposited over the entire surface of the substrate. On the base insulating film 11, an intrinsic semiconductor layer 12 of amorphous silicon (a-Si) and a semiconductor layer protection film 13 made of SiN _X for protecting the upper surface of the intrinsic semiconductor layer 12 are sequentially laminated. Further, from above, n made of a-Si for obtaining ohmic contact with the source electrode and the drain electrode to be formed later.
The type semiconductor layer 14 is laminated. A source electrode 15 and a drain electrode 16 are formed on the n-type semiconductor layer 14.
The source electrode 15 and the drain electrode 16 are made of Ti, Ni, Al or the like.

The pixel electrode 5 is patterned on the base insulating film 11. The thickness of the base insulating film 11 is appropriately 1500Å to 6000Å, but in this embodiment, it is set to 2000Å to 3500Å. Cover the upper surfaces of the TFT 6 and the pixel electrode 5 and cover the entire surface of the substrate with SiN _X.
A protective film 17 made of is formed, and an alignment layer 19 for controlling the alignment of liquid crystal molecules of the liquid crystal layer 18 is deposited on the protective film 17.
A suitable thickness of the protective film 17 is about 2000Å-10000Å, but in this embodiment, it is set to about 5000Å. The base insulating film 11 and the protective film 17 are made of SiO _X , Ta ₂ O ₅ , Al _{2 in} addition to SiN _X.
It may be formed of O ₃ or other oxide or nitride.
Instead of forming the protective film 17 on the entire surface of the substrate, it is possible to form a window structure in which only the TFT 6, the spare TFT 7, the bus wiring, and the like that are not directly involved in the display are covered and the central portion of the pixel electrode 5 is removed.

The sectional structure of the connecting portion 25 will be described with reference to FIG. 1C. A joint metal layer 24 is formed on the base coat film 2. The shape of the joint metal layer 24 is rectangular in plan view as shown in FIG. 1A. The joint metal layer 24 is Ta, A as in the gate bus wiring 3.
It is made of l, Ti, Ni, Mo, etc., and can be patterned simultaneously with the formation of the gate bus wiring 3. The base insulating film 11 described above is deposited on the joint metal layer 24. On the base insulating film 11, the source electrode extension end 8a connected to the source electrode 15 of the spare TFT 7 and the branch wiring 8 connected to the source bus wiring 4 are placed. The source electrode extension end 8a and the branch wiring 8 are separated from each other and maintain a non-conductive state.
Therefore, the spare TFT 7 is not electrically connected to the source bus line 4. The source electrode extension end 8a and the branch wiring 8 are completely covered with a protective film 17.

The base insulating film 11 located between the joint metal layer 24 and the source electrode extended end 8a and the branch wiring 8 also functions as an interlayer insulating film between these metal layer and wiring. The thickness of the interlayer insulating film is preferably 1000Å to 7000Å, but since the base insulating film 11 which also functions as the gate insulating film of the TFTs 6 and 7 is used in this embodiment, the thickness of 2000Å to
It is set to 3500Å.

The protective film 17 is for electrically connecting the branch wiring 8 and the source electrode extension end 8a in a state of being separated from the liquid crystal layer 18 which is a display medium. Therefore, the thickness of the protective film 17 is 15
A value of 00Å to 15000Å is appropriate. In this embodiment, since the protective films of the TFTs 6 and 7 are used, the thickness thereof is set to around 5000Å.

As shown in FIGS. 1B and 1C, a color filter 21 is formed on the inner surface of the other glass substrate 20 facing the glass substrate 1 on which the pixel electrodes 5 are formed. A counter electrode 28 is formed on the color filter 21. In this embodiment, the counter electrode 28 is not formed in the portion of the counter substrate facing the TFT 6 and the connecting portion 25. Such a shape of the counter electrode 28 can be easily formed by patterning using etching or the like. An alignment layer 23 is formed over the entire surface of the counter electrode 28.

A twisted nematic liquid crystal layer 18 is enclosed as a display medium between the pair of glass substrates 1 and 20.
The liquid crystal layer 18 undergoes orientation conversion in response to an applied voltage between the picture element electrode 5 and the counter electrode 22 and is optically modulated. This optical modulation is visually recognized as a display pattern.

All the pixel electrodes 5 of the liquid crystal display device having the above structure are provided with TF
Apply drive voltage via T6. In this manner, when the display device is entirely driven, the pixel defects can be easily visually recognized.
If a pixel defect due to a defect in the TFT 6 has occurred, it can be easily repaired by using the connection portion 25.

FIG. 2 shows a cross-sectional view of the connecting portion 25 after the pixel defect is corrected. As shown by the arrow 26 in FIG. 2, the joint metal layer 24 is irradiated with laser light, infrared rays, an electron beam, and other energy from the outside through the lower glass substrate 1.
In this embodiment, YAG laser light is used. In the overlapping portion of the branch wiring 8, the base insulating film 11 and the joint metal layer 24, the base insulating film 11 undergoes a dielectric breakdown when irradiated with laser light, and the branch wiring 8 and the joint metal layer 24 are melt-connected to each other. Becomes conductive. Similarly, the source electrode extension end 8a and the base insulating film 11
Also in the overlapping portion of the base metal film and the joint metal layer 24, dielectric breakdown of the base insulating film 11 occurs, and the source electrode extension end 8a and the joint metal layer 24 are melt-connected to each other to be in a conductive state. In this way, the branch line 8 and the source electrode extension end 8a are electrically connected via the joint metal layer 24, and the spare TFT 7 is driven by the source bus line 4. In the present embodiment, the laser light is applied from the glass substrate 1 side, but any substrate may be applied as long as the laser light is transmitted therethrough.

When it is necessary to separate the TFT 6 from the pixel electrode 5 due to poor insulation of the TFT 6, the drain electrode 16 of the TFT 6 is irradiated with laser light and cut. By separating the TFT6 and the picture element electrode 5, the picture element electrode 5 is a preliminary TF.
Driven normally by T7.

Even if the pixel defect is corrected by irradiating the laser light in this way, in the present embodiment, the protective film is provided above the connection portion 25 and the TFT 6.
Since 17 is formed, the molten metal is not mixed into the liquid crystal. Also, since the protective film 17 is a transparent insulator,
Laser light passes through it. Therefore, the protective film 17 is not normally destroyed by the laser light. However, the protective film 17 may be destroyed depending on the conditions of laser light irradiation, the material and shape of the joint metal layer 24, the source electrode extension end 8a, the branch wiring 8, the protective film 17, and the like. In this embodiment, since the counter electrode 28 provided on the counter substrate 21 is formed in a portion other than the portion facing the connecting portion 25 and the TFT 6, the protective film 17 is destroyed by laser light irradiation and melted. Even if metal is mixed in the liquid crystal layer 18, it does not come into contact with the counter electrode 28. Therefore,
In this embodiment, by irradiating the connecting portion 25 with a laser beam, the pixel defect can be surely corrected.

Although a transmissive liquid crystal display device is shown in the above embodiment,
The present invention can be applied to a reflective display device as well. Also,
Although the active matrix liquid crystal display device using the TFT has been described in the above embodiment, the present invention is not limited to this. The present invention can also be applied to a wide range of display devices using various switching elements such as MIM elements, diodes, and varistor. Further, it can be applied to various display devices using a thin film light emitting layer, a dispersion type EL light emitting layer, a plasma light emitter, etc. as a display medium.

Further, in the above embodiment, the base coat film 2 does not necessarily have to be provided, and can be omitted.

(Effects of the Invention) In the active matrix display device of the present invention, since the extended end of the signal input terminal of the preliminary switching element and the branch wiring can be electrically connected by irradiating the connecting portion with light energy, the switching element is not defective. At this time, the signal line and the pixel electrode can be electrically connected via the preliminary switching element. Therefore, in the state of the display device in which the generation position of the picture element defect can be easily specified, the picture element defect due to the defect of the switching element can be surely corrected, so that the inspection process and the correction process are facilitated and the mass productivity is secured. Therefore, the present invention
This contributes to cost reduction as a display device.

Further, since the active matrix display device of the present invention has the protective film, it prevents the molten metal generated when the above-mentioned connection portion is irradiated with light energy from coming out of the protective film and coming into contact with the counter substrate side. This makes it possible to prevent the occurrence of new picture element defects. Further, since the counter electrode is formed in a portion other than the portion facing the connection portion, even if the molten metal breaks the protective film and comes into contact with the counter substrate side, it is difficult to contact the counter electrode. It is possible to prevent the occurrence of picture element defects. Further, even if the molten metal breaks through the protective film and goes out, the moving speed becomes slow and the contact area to the counter substrate side becomes narrow, so that it is not necessary to make the size of the counter electrode too small, and one pixel is not necessary. The display area per hit can be increased.

[Brief description of drawings]

FIG. 1A is a plan view of an active matrix substrate used in an embodiment of the display device of the present invention, and FIGS. 1B and 1C show
A display device using the active matrix substrate of FIG.
Sectional views taken along the lines B-B and C-C of FIG. 1A, respectively, FIG. 2 is a sectional view of a connection portion used for repairing pixel defects, and FIG. 3 is an active matrix display. FIG. 4 is a sectional view in the vicinity of a TFT of an improved example of the device, and FIG. 4 is a sectional view in the vicinity of a connection part of the improved example of the active matrix display device. 1,20 …… Glass substrate, 3 …… Gate bus wiring, 4 …… Source bus wiring, 5 …… Pixel electrode, 6 …… TFT, 7 …… Spare TFT, 8 …… Branch wiring, 8a Source electrode extension Terminal, 9 ... Gate electrode, 11 ... Base insulating film, 15,15a ... Source electrode, 16,16a ... Drain electrode, 17 ... Protective film, 18 ... Liquid crystal layer, 19,23 ... Alignment Layers, 21 ... Color filters, 24 ...
… Metal joint layer, 25 …… connection part, 28 …… counter electrode.

Front page continuation (72) Inventor Mikio Katayama 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (56) References JP 62-22455 (JP, A) JP 60-262134 (JP) , A) JP-A-60-55382 (JP, A)

Claims (1)

(57) [Claims] 1. A pair of opposed substrates, at least one of which has a light-transmitting property, a display medium which is inserted between the substrates and whose optical characteristics are modulated in response to an applied voltage, and one of the pair of substrates. Pixel electrodes arranged in a matrix on the inner surface of one substrate, switching elements and preliminary switching elements electrically connected to the respective pixel electrodes, and scanning connected to the switching elements and the preliminary switching elements. Line, a signal line connected to the switching element, and a counter electrode formed on the inner surface of the substrate facing the one substrate, and the extended end of the signal input terminal of the preliminary switching element and the A branch wiring branched from the signal line is provided with a connection portion that is placed in close proximity to the branch wiring through at least an insulating film, and when the switching element is defective, the connection portion is irradiated with light energy. The extension end of the signal input terminal of the preliminary switching element and the branch wiring are electrically connected to each other, and further, in order to prevent the occurrence of defects at the time of irradiation of the light energy, the counter electrode is An active matrix display device which is formed in a portion other than a portion facing the connection portion and has a protective film which covers at least the switching element, the preliminary switching element, the signal line and the scanning line.