JPH04331923A - Active matrix display device - Google Patents

Abstract

PURPOSE:To realize the active matrix display device equipped with a redundant structure which secures correct a picture element defect. CONSTITUTION:Conductor parts 47 are formed at the corner parts of a picture element electrode 41 corresponding to the opposite sides from parts where TFTs 31 are formed, and source bus line projection parts 24 which are formed projecting from source bus lines 23 to the picture element electrode 41 are superposed on the base end parts of the conductor parts 47 across insulating films. Further, conductor pieces 48 which are connected electrically to the picture element electrode 41 are superposed on the tip parts of the conductor parts 47 while covering the entire surfaces of the tip parts. The overlap parts between the bus line projection parts 24 and conductor parts 47 and the overlap parts between the conductor parts 47 and conductor pieces 48 are irradiated with laser light. Consequently, the source bus line projection parts 24 and conductor parts 47, and conductor parts 47 and conductor pieces 48 are connected electrically and respectively, so the picture element electrode 41 and source bus lines 23 are connected eventually.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention applies a driving signal to a display picture element electrode through a switching element.
The present invention relates to a display device that performs display, and particularly relates to an active matrix drive type display device that performs high-density display by arranging picture element electrodes in a matrix.

0002

2. Description of the Related Art Conventionally, in liquid crystal display devices, EL display devices, plasma display devices, etc., a display pattern is formed on a screen by selectively driving picture element electrodes arranged in a matrix. As a display pixel selection method,
An active matrix driving method is known in which individual independent picture element electrodes are arranged and a switching element is connected to each of the picture element electrodes to drive display. As switching elements for selectively driving picture element electrodes, TFT (thin film transistor) elements, MIM (metal-insulating layer-metal) elements, MOS transistor elements, diodes, varistors, etc. are generally used. A voltage applied between opposing electrodes is switched by a switching element to optically modulate a display medium such as a liquid crystal, an EL light-emitting layer, or a plasma light-emitting material interposed between both electrodes, and the optical modulation is performed by switching the voltage applied between opposing electrodes. is visually recognized as a display pattern. Such an active matrix drive system is capable of high-contrast display and has been put to practical use in liquid crystal televisions, word processors, computer terminal display devices, and the like.

By the way, in such an active matrix display device, for example, if a switching element is formed as a defective element, the signal that should originally be given is not input to the picture element electrode connected to the defective element.
On the display screen, the defect is recognized as a point-like pixel defect, that is, a point defect. Such point defects significantly impair the display quality of the display device and become a big problem from the viewpoint of product yield.

The main causes of pixel defects can be broadly classified into the following two types. One is a defect (hereinafter referred to as ON defect) that occurs because the pixel electrode cannot be sufficiently charged within the time when the switching element is selected by the scanning signal (signal from the gate bus line). is a defect (hereinafter referred to as OFF defect) in which the charge charged in the picture element electrode leaks when the switching element is not selected.

[0005] Here, ON failure is caused by a failure of the switching element, while OFF failure is caused by electrical leakage occurring through the switching element or between the picture element electrode and the bus line. There are two types. ON
In both cases of failure and OFF failure, the voltage applied between the picture element electrode and the counter electrode does not reach the required value, so the normally white mode (the voltage applied to the liquid crystal is 0)
When using a display mode in which the light transmittance is at its maximum when In this case, it will look like a sunspot.

[0006] If such point defects are discovered during the manufacturing stage of the substrate on which the switching elements are disposed, they can be corrected by laser trimming or the like. However, it is extremely difficult to detect such point defects from among a huge number of picture elements during the production of the substrate, and considering the manufacturing time and manufacturing cost, it can be said that it is impossible at a mass production level. In particular, it can be said that this is completely impossible for large display panels with 100,000 to 500,000 picture elements.

[0007]Recently, therefore, various active matrix display devices having structures that can easily detect and repair point defects of this type have been proposed, one example of which will be described below. There is an active matrix display device that has a redundant structure. In this active matrix display device, point defects are detected by enclosing a liquid crystal and making the active matrix display device into a state where it can be turned on.Then, the pixel electrode of the defective pixel and the nearest source bus line are connected to each other using glass. A method is used to repair point defects by irradiating a laser through the substrate to create electrical continuity (short circuit).

When the pixel electrode of the defective pixel and the nearest source bus line are electrically connected as described above,
Regardless of the signal from the gate bus line, the signal from the source bus line is input as is to the picture element electrode of the defective picture element. A normal picture element (normal picture element) charges only the source signal supplied within the selection time of the gate bus line and holds this for one cycle (the time until the next selection time comes). In this case, the source signal is always charged regardless of whether the gate bus line is selected or not. Therefore, in this case, the actual value of the source voltage input during one cycle is applied to the liquid crystal. Therefore, the defective picture element lights up at the average brightness of all the picture elements attached to the source bus line to which the defective picture element belongs. This state is neither a perfect bright spot nor a sunspot. As a result, although the repaired picture element is not operating normally, it is in a state where it is extremely difficult to distinguish it as a point defect, and it can be said that the point defect has been substantially repaired.

FIGS. 6 and 7 show a conventional example of an active matrix display device having the above-described redundant structure. Figure 6
In the conventional example shown in FIG.
It has a redundant structure for short-circuiting 3 and 3.

In the redundant structure, point defects are detected and repaired as follows. That is, for detection, a glass substrate on which the TFT 31 and the like shown in the figure are disposed is bonded to a glass substrate on the counter electrode side, a liquid crystal is sealed between both glass substrates, and in this state, the gate bus line 21 and the source bus line 23 are connected to each other. A suitable signal is then applied to the counter electrode to light up the picture element, and an inspector visually inspects the lighting state to detect point defects. If a point defect is found, the picture element is then repaired by irradiation with energy such as a laser beam.

Specifically, a source bus line protrusion 24 is formed to protrude from the source bus line 23 toward the picture element electrode 41, and a conductor is overlapped with the source bus line protrusion 24 via an insulating film. A laser beam is irradiated to the overlapping portion with the conductor portion 47 and the overlapping portion between the conductor portion 47 and the conductor piece 48 superimposed on the tip of the conductor portion 47 via an insulating film, and the corresponding portion is made into a small Punch out at the spot. As a result, the conductor part 47 and the gate bus line protruding part 24 and the conductor part 47 and the conductor piece 4 are inserted through the periphery of the punched hole.
8 are electrically connected, and as a result, the picture element electrode 41 and the source bus line 23 are short-circuited. Therefore, the picture element electrode 41 is always at the same potential as the source bus line 23, and this achieves the purpose.

On the other hand, in the conventional example shown in FIG. 7, a redundant structure is formed in the left corner of the figure, and the redundant structure extends from the gate bus line 21a adjacent to the gate bus line 21 on which the TFT 31 is formed to the pixel electrode 41. The gate bus line protrusion 25 is formed to protrude toward the gate bus line protrusion 2.
A structure in which a source bus line protrusion 24 is superimposed on the base end of the gate bus line protrusion 25 via an insulating film, and a conductor piece 48 is superimposed on the tip of the gate bus line protrusion 25 via an insulating film. Consisting of Due to the presence of the insulating film, these are electrically insulated in the initial state.

Similarly to the above, when the liquid crystal is turned on with the liquid crystal enclosed and a point defect is detected, a laser beam is first irradiated through the glass substrate to the base of the gate bus line protrusion 25. disconnect from. This results in
The gate bus line protrusion 25 is connected to the gate bus line 21a.
It is electrically isolated from the Subsequently, the overlapping portion of the gate bus line protrusion 25 and the source bus line protrusion 24 and the overlapping portion of the gate bus line protrusion 25 and the conductor piece 48
The second and third laser beam irradiations are applied to the superimposed portions of the two. As a result, the gate bus line protrusion 25 and the source bus line protrusion 24 and the gate bus line protrusion 25 and the conductor piece 24 are electrically connected, respectively.
As a result, the source bus line 23 and the picture element electricity source 41 are short-circuited. As a result, point defects are repaired in the same manner as described above.

Here, the short circuit between the source bus line 23 and the picture element electrode 41 is caused by the TFT 31 as a switching element.
must be larger than the resistance value during the selected period. This is because unless the signal from the source bus line 23, which changes every time the TFT 31 is written, is quickly charged into the picture element, the actual value of the voltage of the source signal applied to the picture element electrode 41 will become small. . The above-mentioned repair process using laser light can reliably meet these conditions.

[0015]

[Problems to be Solved by the Invention]) In the conventional example with the above-mentioned redundant structure, in order to substantially repair a point defect, it is necessary to ensure that the conductors superimposed above and below are electrically connected after laser irradiation. It becomes necessary. The conduction between the upper and lower conductors is achieved by drilling a small spot-like hole in the overlapping portion with a laser as described above, and conducting between the upper and lower conductors around the hole. In the conventional redundant structure, the size of the conductor piece 48 is at most 10 μm square, and this portion is punched out with a laser.

By the way, the machining accuracy of a typical YAG laser (wavelength: 1053 nm) that is normally used for such machining is at a level that can machine a hole several μm square. Therefore,
When a hole is formed in the conductor piece 48 using a YAG laser, the area of the hole is slightly smaller than the area of the conductor piece 48. Therefore, as shown in FIG. 8A, when the center of the conductor piece 48 is irradiated with a laser beam, the laser beam irradiation area 51 is slightly smaller than the area of the conductor piece 48, so that the conductor piece 48 may be completely crushed, leading to a situation where there is no electrical conduction between the upper and lower parts.

[0017] In order to prevent such a problem, the method shown in Fig. 8 (
As shown in b), a portion of the conductor piece 48 closer to the end may be irradiated with a laser beam. However, according to this method, as shown by the hatched line 52 in FIG. 8(b), the circumference of the hole where the upper and lower parts should be electrically connected is short, and the connection probability cannot be said to be sufficient. Therefore, it is insufficient to ensure electrical continuity between the upper and lower sides.

Furthermore, in order to prevent the conductor pieces 48 from scattering due to YAG laser irradiation, the laser beam irradiation area 5
1, the area of the redundant structure including the conductor piece 48 may be made sufficiently large. However, increasing the size of redundant structures that are essentially unnecessary cannot be said to be an effective solution.

The present invention solves the problems of the prior art, and provides an active matrix display device that can reliably repair point defects without increasing the size of the redundant structure, and can significantly improve product yield. The purpose is to provide.

[0020]

[Means for Solving the Problems] The active matrix display device of the present invention has scanning lines and signal lines wired in a grid pattern on one of a pair of insulating substrates, and the scanning lines and signal lines In an active matrix liquid crystal display device in which pixel electrodes are arranged in the enclosed area, and switching elements are connected to the pixel electrodes, the scanning lines, and the signal lines, respectively, the signal lines are connected to the pixel electrodes. a signal line protrusion formed protruding from the pixel electrode and not in electrical contact with the picture element electrode; one end side overlapping the signal line protrusion with an insulating film interposed therebetween; the signal line, the scanning line, and the picture element electrode; a conductor portion that is not in electrical contact with the pixel electrode, and a conductor portion that is superimposed on the other end side of the conductor portion with an insulating film in between so as to completely cover the other terminal portion, and that is in electrical contact with the pixel electrode. , and a conductor piece that is not in electrical contact with the signal line protrusion, thereby achieving the above object.

[0021] A scanning line protrusion formed protruding from a scanning line adjacent to the scanning line toward the picture element electrode and an additional capacitance bus line forming an additional capacitance below the picture element electrode to the picture element electrode. The conductor portion may also be formed by an additional capacitance bus line protrusion formed to protrude toward the conductor.

[0022]

[Operation] In the active matrix display device having the above configuration, the substrate on which the switching elements are disposed and the substrate on the counter electrode side are bonded together, liquid crystal is sealed between them, and then the scanning lines, signal lines, and pixel electrodes are connected to each other. When an appropriate drive signal is applied, the active matrix display device displays a display pattern, so that point defects can be easily found by visually checking the display screen.

When a point defect is found, a laser beam is irradiated onto the overlapping portion of the conductor portion and the conductor piece, more specifically onto the irradiation area 51 shown in FIG. In FIG. 3, the conductor piece 48 is overlapped with an insulating film interposed therebetween so as to completely cover the tip of the conductor portion 47 in a state where it slightly protrudes from the tip of the conductor portion 47 below. In addition, the irradiation area 51
A part of the conductor portion 47 protrudes from the tip.

When such an irradiation area 51 is irradiated with a laser beam, the laser beam pierces through the insulating film interposed between the conductor portion 47 and the conductor piece 48, and as a result, the area shown by the hatched line 52 in FIG. The conductor piece 48 and the conductor portion 47 are short-circuited at the end of the irradiation area 51 .

At this time, according to the above-described redundant structure, as is clear from the figure, a sufficient circumferential length can be secured at the connection portion between the conductor piece 48 and the conductor portion 47. Furthermore, since the irradiation area is selected at a position closer to the end of the overlapping portion, the conductor pieces 48 are not scattered due to laser irradiation. Therefore, according to such a redundant structure, the probability of connection between the upper and lower conductors can be sufficiently increased, and it becomes possible to ensure conduction between the two.

[0026]

[Examples] Examples of the present invention will be described below.

FIGS. 1 to 3 show an active matrix display device according to this embodiment, and this display device has a liquid crystal 18 sealed between a pair of upper and lower transparent insulating substrates 1 and 2. On the lower substrate 1, a plurality of gate bus lines 21, 21, . . . which function as scanning lines, and a plurality of source bus lines 23, . Picture element electrodes 41 are arranged in a matrix in each rectangular area surrounded by 23. A gate bus branch line 22 is formed from the gate bus line 21, and a T bus branch line 22 is formed at the tip of the gate bus branch line 22.
FT31 is formed. The TFT 31 functions as a switching element and is connected to the picture element electrode 41.

A rectangular conductor portion 47 whose tip overlaps the picture element electrode 41 is formed at a corner of the picture element electrode 41 corresponding to the opposite side of the TFT 31 forming portion. The conductor portion 4
A source bus line protrusion 24 protruding from the source bus line 23 is formed above the base end of the gate insulating film 13 .
(see FIG. 2). In addition, the conductor portion 4
A conductor piece 48 that covers the entire surface of the tip and whose tip protrudes beyond the conductor portion 47 is superimposed above the tip of the conductor 7 with the gate insulating film 13 interposed therebetween. The conductor piece 48 has a rectangular shape that is long in the direction intersecting the conductor portion 47 .

The details of each part will be explained below according to the production procedure. As shown in FIG. 2, first, a gate bus line 21 is formed on a transparent insulating substrate 1. This fabrication is generally performed using Ta
, Ti, Al, Cr, etc., in a single layer or multiple layers are deposited on the transparent insulating substrate 1 by sputtering, and then patterned. At this time, the gate bus branch line 22 and the conductor portion 47 are simultaneously produced. In this example, a glass substrate 1 was used as the transparent insulating substrate 1. Note that an insulating film such as Ta2O5 may be formed as a base coat film under the gate bus line 21.

Next, a gate insulating film 13 is laminated on the gate bus line 21 (including the gate bus branch line 22 and the conductor portion 47). In this example, a SiNx film was deposited to a thickness of 300 nm by plasma CVD to form the gate insulating film 13. Note that before forming the gate insulating film 13, the gate bus line 21 may be anodized to form the oxide film 12 made of Ta2O5.

Next, the semiconductor layer 14 and the etching stopper layer 15 are deposited on the gate insulating film 1 by plasma CVD.
Continuously form on top of 3. The semiconductor layer 14 is made of an amorphous silicon (a-Si) layer, and the etching stopper layer 15 is made of a SiNx layer. The respective film thicknesses are 30 nm and 200 nm. Then, the etching stopper layer 15 is patterned, and then a phosphorus-doped n+ type a-Si layer 16 is formed to a thickness of 80 nm by plasma CVD.
Laminated to a thickness of . This n+ type a-Si layer 16 is formed to improve the ohmic contact between the semiconductor layer 14 and the source electrode 32 or drain electrode 33 laminated thereafter.

Next, the n+ type a-Si layer 16 is patterned, and then a source metal is deposited by sputtering. Source metals generally include Ti, Al,
Although Mo, Cr, etc. are used, Ti was used in this example. Then, the Ti metal layer is patterned to obtain a source electrode 32 and a drain electrode 33. At this time, the source bus line 23, source bus line protrusion 24, and conductor piece 48 are formed at the same time. As a result, a TFT 31 whose structure is shown in FIG. 2 is manufactured.

Next, a transparent conductive material that will become the picture element electrode 41 is laminated. In this example, I
TO (indium tin oxide) is laminated by a sputtering method, and this is patterned to obtain a picture element electrode 41. The picture element electrode 41 is laminated in a rectangular area surrounded by the gate bus line 21 and the source bus line 23 as described above, and as shown in FIG.
Laminated on the end of the drain electrode 33 of the FT 31, and
It is laminated on the conductor piece 48. As a result, the picture element electrode 4
1 and the drain electrode 33 of the TFT 31 and the conductor piece 44
becomes conductive.

A protective film 17 made of SiNx is deposited over the entire surface of the glass substrate 1 on which the picture element electrodes 41 are formed. The protective film 17 may be removed in the center of the picture element electrode 41 to form a window. An alignment film 19 is formed on the protective film 17 . The protective film 17 may also have a window-perforated shape with its central portion removed. As shown in FIG. 2, a counter electrode 3 and an alignment film 9 are formed on a glass substrate 2 facing the glass substrate 1. Then, a liquid crystal 18 is sealed between these glass substrates 1 and 2, and the active matrix display device of this embodiment is fabricated.

Next, a method of repairing a pixel defect when it occurs in the active matrix display device of this embodiment will be explained. Normally, the picture element electrode 41 is driven by the TFT 31, and as long as the TFT 31 operates normally, the picture element in the area surrounded by the gate bus line 21 and the source bus line 23 operates normally, and there are no display problems. Does not occur. However, if the TFT 31 becomes abnormal or a weak current leak occurs between the source bus line 23 and the picture element electrode 41, a picture element defect appears and is recognized as a display problem. In this embodiment, this is repaired as follows.

That is, when the active matrix display device is driven and pixel defects are confirmed, first, the conductor portion 4
7 and the source bus line protrusion 24 and the overlapped portion between the conductor section 47 and the conductor piece 48 are irradiated with YAG laser light as an example of optical energy. In the portion irradiated with the laser light, the laser light breaks through the gate insulating film 13 between the above-mentioned upper and lower conductors. As a result, the upper and lower conductors are short-circuited at the end of the portion irradiated with the laser beam.

Note that the laser beam irradiation area at the overlapped portion of the conductor portion 47 and the conductor piece 48 is an irradiation area 51 shown by a broken line in FIG. A portion of the irradiation area 51 protrudes from the tip of the conductor portion 47, and forming the protrusion has the advantage that the circumference of the connection portion, which will be described below, can be increased.

When the above irradiation area 51 is irradiated with a laser beam, the circumference at the connection portion between the conductor portion 47 and the conductor piece 48 is determined as shown in FIG.
) can be made much larger than the circumference of the above conventional example. Further, as is clear from the figure, the area of the irradiation region 51 is smaller than the area of the conductor piece 48. Therefore, the conductor pieces 48 are not scattered.

By irradiating the above two positions with laser light, the source bus line protrusion 24 and the conductor portion 47 are
are electrically connected, and the conductor portion 47 and the conductor piece 48 are electrically connected. Therefore, as a result, the source bus line 24 and the picture element electrode 41 are short-circuited. Therefore, the pixel in which the point defect has occurred is illuminated with the average brightness of all the pixel elements along the adjacent source bus line 23, making it extremely difficult to visually recognize it as a defect on the display.

Note that the laser beam irradiation can be performed from the back side of the glass substrate 1 or from the glass substrate 2 side.
In the active matrix display device of this example,
The counter electrode side is covered with a light-shielding conductor and cannot be directly irradiated with laser light. Therefore, in this example, irradiation was performed from the back side of the glass substrate. Further, the order of irradiation of the laser beams onto the two positions is not limited to the above order.

FIG. 4 shows another embodiment of the present invention,
In this embodiment, instead of the above-mentioned conductor portion 47, a TFT
The configuration uses a gate bus line protrusion 25 formed to protrude toward the picture element electrode 41 from the gate bus line 21a adjacent to the gate bus line 21 connected to the gate bus line 31. This embodiment has the following advantages.

That is, in general, a structure is often used in which the gate bus line 21 is anodized to form a Ta oxide film on the surface and the insulating film has a two-layer structure to improve insulation. 21, an anodic oxide film is formed at the same time when the gate bus line 21 is anodized, which has the advantage of improving the insulation properties of this portion. Therefore, in order to take advantage of this advantage, this embodiment adopts a configuration in which the conductor portion is formed by the gate bus line protrusion 25 formed to protrude from the gate bus line 21a.

However, in this embodiment, it is necessary to separate the gate bus line protrusion 25 from the gate bus line 21a when irradiating the laser beam. This separation is achieved by irradiating the root portion of the gate bus line protrusion 25 with laser light.

The active matrix display device of this example is manufactured in the same manner as in the above example, and point defects are repaired by connecting the gate bus line protrusion 25 to the gate bus line 21.
After (or before) separation from a, laser light is irradiated to two positions similar to the above embodiment.

FIG. 5 shows still another embodiment of the present invention, in which each picture element electrode 41 has an additional capacitance 72. The additional capacitor 72 is composed of an additional capacitor bus line 26 provided parallel to the gate bus line 21 and the gate insulating film 13 interposed between the picture element electrode 41. To explain a little bit, Gate Bus Line 2
1 is superimposed on the picture element electrode 41, and an additional capacitor 72 shown with diagonal lines in the figure is provided at the overlapped portion of the gate bus line 21 and the picture element electrode 41.
is formed. The additional capacitor bus line 26 is made of the same metal as the gate bus line 21, and is made of the same metal as the gate bus line 21.
They are formed simultaneously during the patterning of the first pattern.

In this embodiment, the same signal as the counter electrode 3 is input to the additional capacitance bus line 24. Therefore, the additional capacitance 42 is connected to the picture element electrode 4 in terms of an electric circuit.
1 and the glass substrate 2 in parallel to the liquid crystal capacitor of the liquid crystal 18 sealed between the liquid crystal 18 and the glass substrate 2. The presence of such an additional capacitor 42 improves the charge retention ability of the picture element electrode 41, and ultimately improves the performance of the display device.

In this embodiment, the conductor portion is formed by an additional capacitor bus line protrusion 27 that is formed to protrude from the additional capacitor bus line 26 toward the picture element electrode 41 side. Repair of point defects in this embodiment is performed in the same manner as in the embodiment shown in FIG.

Although TFTs are used as switching elements in the above embodiments, other switching elements such as MOS transistor elements may also be used. Also, T
The structure of the FT is not limited to that of the above embodiment,
A structure may be used in which the source bus line is placed on the bottom surface and the gate bus line is placed on the top surface.

[0049]

According to the above-described redundant structure of the active matrix display device of the present invention, the probability of connection between the upper and lower conductors after a point defect is repaired can be increased. Therefore, electrical continuity between the upper and lower conductors can be ensured. Further, the conductor does not scatter. Therefore, product yield can be improved,
This is convenient for reducing costs.

[0050] In particular, the active matrix display device according to the second aspect has the advantage that insulation characteristics can be improved.

[0051] In particular, the active matrix display device according to claim 3 has the advantage that display characteristics can be improved.

[Brief explanation of drawings]

FIG. 1 is a plan view of an active matrix display device of the present invention.

FIG. 2 is a sectional view taken along line AA in FIG. 1.

FIG. 3 is an enlarged view of part B in FIG. 1.

FIG. 4 is a plan view showing another embodiment of the invention.

FIG. 5 is a plan view showing still another embodiment of the present invention.

FIG. 6 is a plan view showing a conventional example.

FIG. 7 is a plan view showing another conventional example.

FIG. 8 is a plan view showing the drawbacks of the conventional example.

[Explanation of symbols]

1 Glass substrate on the side where the picture element electrode is arranged 2 Glass substrate on the side where the counter electrode is arranged 3 Counter electrode 13 Gate insulating film 18 Liquid crystal 21 (21a) Gate bus line 22 Gate bus branch line 23 Source bus line 24 Source bus line protrusion 25 Gate bus line protrusion 26 Additional capacitance bus line 27 Additional capacitance bus line protrusion 31 TFT 32 Source electrode 33 Drain electrode 41 Picture element electrode 47 Conductor portion 48 Conductor piece 51 Laser light irradiation area 52 Shaded line 72 indicating the circumference at the connection part Additional capacitance

Claims (3)

[Claims] Claim 1: Scanning lines and signal lines are wired in a grid pattern on one of a pair of insulating substrates, and pixel electrodes are respectively arranged in areas surrounded by the scanning lines and signal lines. In addition, in an active matrix liquid crystal display device in which switching elements are connected to the picture element electrode, the scanning line, and the signal line, respectively, a switching element is formed protruding from the signal line toward the picture element electrode, and is electrically connected to the picture element electrode. a non-contact signal line protrusion, a conductor portion whose one end side is overlapped with the signal line protrusion via an insulating film, and which is not in electrical contact with the signal line, the scanning line, and the pixel electrode; Overlaid on the other end side of the conductor portion with an insulating film interposed therebetween so as to completely cover the other terminal portion, electrically contacting the picture element electrode and not electrically contacting the signal line protruding portion. An active matrix display device comprising a conductive piece. 2. The active matrix display device according to claim 1, wherein the conductor portion is a scanning line protruding portion formed to protrude from a scanning line adjacent to the scanning line toward the picture element electrode. 3. The conductor portion is an additional capacitor bus line protruding portion formed to protrude toward the picture element electrode from an additional capacitor bus line forming an additional capacitor below the picture element electrode. active matrix display device.