JPH0627982B2 - Display device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly, to a so-called active matrix display device driven by using a switching element such as a thin film transistor (hereinafter referred to as TFT).

[Background of the Invention]

The active matrix display, which combines a switching element such as TFT and an electro-optical material such as liquid crystal or electroluminescence, is known as a "liquid crystal matrix display" by BJ Lukar as a display suitable for a large screen or high definition.・ E ・
EE 59, 1566 (1971) [(B, J, Lecher)
“Liquid Crystal Matrix Display” Proc IEEE 59, 156
6 (1971)] ”, and research and development has been underway. In this display, TFT elements are arranged at the intersections of the scanning wiring (X wiring) and the signal wiring (Y wiring), and
The gate electrode of the FT element is connected to the scanning wiring, the drain electrode of each TFT element is connected to the signal wiring, and the source electrode is connected to the transparent electrode for applying a voltage to the liquid crystal.

However, in a display with such a structure,
If any of the scanning wiring or the signal wiring is broken, the voltage is not applied to the TFT element connected to the broken wiring, resulting in a linear defect, the display image is deteriorated, and the function as a display is significantly deteriorated. To do. Therefore, practically, the display is not suitable as a product when a line defect due to a cross section of a wiring or the like occurs.
In particular, as the display capacity of the display increases and the total wiring length increases, or as the definition of processing improves and the wiring width decreases, the probability of disconnection of the wiring increases and the manufacturing yield decreases. Atsuta Therefore, JP-A-59
-91479 and Japanese Patent Laid-Open No. 58-111085 have been proposed in which a display device is constructed by a method.

However, in the conventional configuration, when a line defect occurs, unnecessary lines may be cut, or a special material for making a fuse is required.The line defect can be prevented with a simple configuration. Nakatsuta.

[Object of the Invention]

The present invention has been made in view of the above conventional problems,
It is an object of the present invention to provide a display device capable of displaying with a simple circuit configuration even if the wiring is broken.

[Outline of Invention]

According to the present invention, a plurality of signal wirings and a plurality of scanning wirings are arranged in a matrix on a substrate, and a switching element is arranged in a portion of the substrate where each signal wiring and each scanning wiring intersect, In a display device in which an electro-optical material such as liquid crystal or electroluminescence is laminated on this substrate, a drive circuit is directly provided between the wirings of at least one of the signal wiring group and the scanning wiring group outside the display area. The display device is configured to be connected by a resistance element having a value larger than the output resistance to achieve the object.

Example of Invention

Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a preferred embodiment of the present invention. In this embodiment, T is provided at the intersection of the signal wiring 1 and the scanning wiring 2.
An FT element 3 is arranged, and an image display unit having a structure in which a liquid crystal 4 is laminated thereon, and a resistor 5 having a resistance value R at the end of each signal wiring is connected between the signal wirings on the substrate. That is, even if a disconnection occurs at the terminal on the opposite side of the drive circuit that applies communication between the signal wiring 1 and the scanning wiring 2, a voltage can be applied between the wirings.

The resistor 5 may be a resistance element connected outside the display substrate or a resistance element formed on the substrate inside the display. Further, for these resistors, for example, resistors formed by doping a semiconductor film with impurities, channel resistors between the source and drain electrodes of the TFT element, or diodes connected in the antiparallel direction may be used. .

The value R of the resistor 5 is set so that R >> Rout when the output resistance of the drive circuit for driving the signal electrode 1 is Rout.

As described above, in this embodiment, the resistor 5 is provided between the signal wirings 1.
As shown in FIG. 2, since
Even if the signal wiring 1 is disconnected, the signal voltage Vx from another signal wiring
Is applied to pixels below the point where the disconnection occurs. Moreover,
The value of this voltage Vx is the signal voltage Vk−1,
Output resistance Rout of the drive circuit for applying Vk, Vk + 1, ...
Is set to R >> Rout, Vx = (Vk
It can be calculated as -1 + Vk + 1) / 2. That is, the voltage of the average value of the applied voltages of the two adjacent signal lines 1 is applied to the pixels below the disconnection occurrence point 6. Therefore, even when an active matrix display has many halftones as in the case of a telescopic image display and an image in which the brightness of neighboring pixels changes gently is often displayed, the signal voltage waveform is as shown in FIG. The change does not change rapidly between the signal wirings 1 and the change is gradual.
Then, at this time, the voltage Vx applied to the pixel connected to the signal wiring 1 in which the disconnection has occurred becomes a value close to the original signal voltage Vk, and a natural image can be displayed.

Further, when no disconnection occurs in the signal wiring 1, there is a relation of R >> Rout between the output resistance Rout of the drive circuit and the resistance 5 connected to the signal wiring 1, so that there is no signal voltage. It has no effect.

FIG. 4 shows the configuration of an embodiment when applied to a color display panel.

In this embodiment, a color filter is used for a color display panel, filters of three colors R (red), G (green), and B (blue) are arranged in a checkered pattern or diagonally in a mosaic pattern, and each color The case where the repetition cycle is 3 pixels is shown. Also in this embodiment, since the resistor 5 is wired in a specific turn of the signal wiring, even if the signal wiring 1 is disconnected as in the above-described embodiment, the signal voltage is transmitted from the adjacent pixels of the same color via the resistor 5. Since the voltage is applied, a natural image can be displayed in color even if the signal wiring is broken.

FIG. 5 shows a configuration of a display panel in which two signal wirings are set as one set and a resistor 5 having a resistance value R is connected between the signal wirings. In the present embodiment, the signal wirings Y1 to Y8
Even if one of the signal wirings is broken, a voltage is applied from another signal wiring. Therefore, the pixels below the disconnection point have the same display state as the signal wiring connected by the resistor 5. Therefore, in the present embodiment, the number of resistors 5 can be reduced as compared with that in FIG. Further, in this embodiment, the resistance R is connected to all the signal wirings of all the signal wirings Y1 to Y8, but when the number of the broken portions is small, an external resistor is connected to the signal wiring having the broken wiring. By doing so, the same effect can be obtained.
Furthermore, even if a plurality of signal wirings are put together and a resistor R is connected between these signal wirings, the same effect as that of FIG. 1 can be obtained.

FIG. 6 shows a configuration of a display panel in which a resistor 5 having a resistance value R is inserted in each signal line 1 and the resistors 5 are commonly connected.

In this embodiment, when a disconnection occurs in the k-th column signal wiring, the signal voltage is applied to the disconnection occurrence location. Since a voltage of (V ₁ + V ₂ + ... + V (k−1) + V (k + 1) ... + V (n + 1)) is applied, an image can be displayed in a natural state even if the signal wiring is broken.

Next, an embodiment in which the present invention is applied to the scanning wiring 2 will be described. FIG. 7 shows a configuration in which a resistor 5 having a resistance value R is connected to each line end of the scanning wiring 2.
Also in this embodiment, the resistance value R of the resistor 5 is set to the scanning wiring 2
The output resistance Rout of the driving circuit is set to R >> Rout. Therefore, when a disconnection occurs in the k-th scanning line, the voltage Vk applied to the gate electrode of the pixel after the disconnection in the k-th row is Vk = (V (k−1) + V (k + 1)) / 2.

However, V (k + 1) and V (K + 1) are respectively in the (k−1) th line,
And the scanning voltage applied to the scanning wiring of the (k + 1) th row. FIG. 8 shows drive waveforms and voltage waveforms applied to the liquid crystal layer when the display panel shown in FIG. 7 is used. 8th
FIG. 6A shows a scanning voltage waveform applied to the gate electrode of the TFT of each pixel when there is no disconnection. This waveform is R >>
Due to the relationship of the resistance 5 serving as Rout, the waveform is obtained when the resistance 5 of each scanning wiring 2 is not connected. Further, FIG. 8A shows a voltage waveform applied to the gate electrode of the TFT from the pixel after the disconnection point when the disconnection occurs in the scanning wiring 2. Further, in the figure, V ₂ indicates a voltage waveform at a disconnection point.
Since this voltage is the average value of the voltages applied to the two adjacent scanning wirings 2 as shown in the above-mentioned formula, the peak value of the voltage is almost half.

Here, this peak value is used as the threshold voltage Vt of the TFT element.
It is set to be larger than k. At this time, assuming that the signal voltage Vy as shown in FIG. 8C is applied to the pixel of V ₂ whose scanning voltage is (b), the voltage V _LC applied to the liquid crystal layer of this pixel. Has the waveform shown in FIG. 8 (c). That is, the scanning voltage is applied twice in one frame, but generally, the time for one frame is sufficiently longer than the time for applying the scanning voltage for two times, so that the voltage applied to the liquid crystal layer is delayed. Scan pulse, that is, the scan pulse synchronized with the voltage V ₃ shown in FIG. Therefore, since the light transmittance of the liquid crystal depends on the effective value of the voltage applied to the liquid crystal layer, the same display is performed by the two scanning wirings 2 when a disconnection occurs. As described above, when the display state changes gently, the line defect can be made inconspicuous.

FIG. 9 shows an embodiment in which two scanning wirings 2 are connected as a set via a resistor 5. In the present embodiment, when a disconnection occurs in the scanning wiring 2, a scanning voltage is applied to the disconnected portion via the resistor 5. Therefore, it is possible to prevent the peak value of the scanning pulse from being lowered as in the case of FIG.

FIG. 10 shows an embodiment in which the present invention is applied to both the scanning wiring 2 and the signal wiring 1. In this embodiment, the scanning lines 2 and the signal lines 1 are alternately drawn out one by one from the opposite side. Further, even if the resistor 5 is connected to the input terminal side, if the resistance value R of the resistor 5 is made sufficiently larger than the output resistance Rout of the drive circuit, the applied voltage will not be affected.

In this embodiment, even if both the scanning wiring 2 and the signal wiring 1 are broken, a natural image can be displayed.

FIG. 11 shows the configuration of a specific embodiment for realizing the present invention. In this embodiment, a signal input line 11, a signal side driving circuit diagram including a switch FET 9 for switching a signal from the signal input line 11 and a shift register 10 for driving the FET 9 and each signal wiring 1 are connected. It is composed of a FET 7 and a gate bias line 8 of the FET 7. Here, for example, if the one shown in FIG. 11 is formed on the same substrate, FE
T9 and FET7 the TFT, and the channel length of the channel width _{W 1} and TFT7 a channel length _{L 1} of the TFT 9 _{L 2}
The respective TFTs are formed so that the relationship of W ₁ / L ₁ >> W ₂ / L ₂ exists between and the channel width W ₂ .
An example of a plane pattern for realizing the one shown in FIG. 11 is shown in FIG. This TFT element can be manufactured by the same process as the TFT element of the image display portion, and the reliability can be improved without complicating the manufacturing process of the display substrate.

As described above, in each of the above-described embodiments, the one mainly applied to the active matrix display using the TFT is described. However, the present invention is not limited to the normal matrix display or the diode as shown in FIG. It can also be applied to displays using terminal elements.

〔The invention's effect〕

As described above, according to the present invention, a resistance element having a resistance value larger than the output resistance of the wiring drive circuit is provided in each wiring line that describes the display area of at least one wiring group of the signal wiring group and the scanning wiring group. Since the wirings are inserted and the wirings are directly connected by the resistance elements, even if the wirings are broken in the display device, line defects are not noticeable and a display image close to natural is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention, FIG. 2 is a view for explaining the action when a wire break occurs in the display shown in FIG. 1, and FIG. 3 is shown in FIG. FIG. 4 is a configuration diagram of a second embodiment applied to a color display panel, FIG. 5 is a configuration diagram showing a third embodiment of the present invention, and FIG. 4 is a block diagram showing a fourth embodiment of the invention, FIG. 7 is a block diagram showing a fifth embodiment of the present invention, FIG. 8 is a waveform diagram of a signal used for the display of FIG. 7, and FIG. 9 is the present invention. 6 is a block diagram of a sixth embodiment of the present invention,
FIG. 0 is a block diagram showing a seventh embodiment of the present invention, FIG. 11 is a block diagram showing an eighth embodiment of the present invention, FIG. 12 is a plan pattern diagram of FIG. 11, and FIG. It is a block diagram which shows 9th Example. 1 ... Signal wiring, 2 ... scanning wiring, 3 ... TFT element,
4 ... Liquid crystal, 5 ... Resistor, 6 ... Disconnection point, 7 ... TF
T element, 8 ... Bias wiring, 9 ... TFT element, 10
...... Shift register.

Claims (4)

[Claims] 1. A plurality of signal wirings and a plurality of scanning wirings are arranged in a matrix on a substrate, and a switching element is arranged at a portion of the substrate where each signal wiring and each scanning wiring intersect. In a display device in which a liquid crystal and an electroluminescent electro-optic material are laminated on the substrate, an output resistance of a drive circuit is directly provided between wirings of at least one of the signal wiring group and the scanning wiring group outside a display area. A display device characterized by being connected by a resistance element having a larger value. 2. The display device according to claim 1, wherein the resistance element is a resistor. 3. The display device according to claim 1, wherein the resistance element is a transistor. 4. A display device according to claim 1, wherein the resistance element is a diode.