JPH11295761A - Display device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation of display line defects by constituting a driving circuit to be controlled by a bus adjacent to the other end part of a second bus group on a substrate. SOLUTION: In this matrix type display device, display signals are transmitted to a first bus group, scanning signals are transmitted to the second bus group respectively and display units provided corresponding to the intersections of first buses and second buses are driven by both signals. Relating to device, A control driving circuit 5 to be controlled by the bus adjacent to the other end part of the second bus group is constituted on the substrate. That is, the control driving circuit 5 for connecting scanning buses is simultaneously formed on the other end part side of a scanning bus driving circuit part 3 in addition to a source bus driving circuit part 2 and the scanning bus driving circuit part 3 as a part of a driving circuit part for respectively impressing the display signals and the scanning signals on a liquid crystal display panel 1. Thus, even in the case that a disconnected part is present in a specified bus, controlled signals are transmitted from the other bus without disconnection and the signals are impressed to respective display elements.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a display device, and more particularly to a matrix type display device.

[0002]

2. Description of the Related Art A polysilicon thin film transistor (hereinafter referred to as "polysilicon thin film transistor")
A matrix liquid crystal display panel using a switching element of a p-Si TFT) has a feature that a driver circuit can be built in on the same substrate as a pixel transistor included in a display portion. In recent years, there has been an increasing need for a large screen and high definition of a matrix type liquid crystal display panel such as a TFT liquid crystal display panel, and developments meeting market needs have been made.

The driving of a liquid crystal display device having such a liquid crystal display panel of a TFT matrix array is generally carried out, as shown in Japanese Patent Publication No. 4-3552.
It is performed by point-sequential driving in which display signals sent continuously in time are sequentially taken into signal lines of each pixel column. In the point-sequential driving method, the circuit configuration is simple because there is only an analog switch connected to each source bus and a shift register that sequentially sends a pulse for turning on the analog switch by a dot timing signal. However,
When the resolution of the screen is increased, the frequency of the dot timing signal is increased because the one-frame period is constant, and the time during which the analog switch is turned on is shortened, resulting in an inconvenience of insufficient writing to the liquid crystal. In order to eliminate such inconveniences, for a panel requiring such a high driving frequency (dot timing signal), a method of lowering the driving frequency by operating shift shifters in parallel is generally adopted.

Hereinafter, a general driving method of a liquid crystal display panel will be described with reference to the drawings.

FIG. 6 is a conceptual diagram of a general p-Si TFT liquid crystal display panel driving device. In FIG. 6, 1 is a liquid crystal display panel, 2 is a source bus driving circuit, and 3 is a scanning bus driving circuit. ..., S1, S2 ... Sn
Are a plurality of liquid crystal display panel source buses, V1, V2,.
Vn is a plurality of liquid crystal display panel scanning buses. The switching elements 30a, 30b, 30c,..., 31 are provided at the intersections of the plurality of source buses and the plurality of scanning buses.
a, 31b, 31c,... are provided. FIG. 7 shows FIG.
FIG. 3 is an electrical block diagram of the source bus driving circuit section 2 of FIG.
Reference numeral 6 denotes a shift register unit, and reference numeral 7 denotes a buffer unit. The analog switch TG is controlled by a dot timing signal sent from the dot timing signal lines Q1, Q2, Q3...
11 ... TG13, TG21 ... TG23, TG31 ...
TG33,... Are selected to be in a conductive state (selected state) or in a cutoff state (non-selected state). The analog switches TG11... TG1 during the period (selection period) selected to be conductive.
3, TG21 ... TG23, TG31 ... TG33, ...
Operates on display signals sent from the display signal lines R, G, and B, and performs liquid crystal display from switching elements on the selected scanning bus and source bus.

When a bus such as a plurality of liquid crystal display panel source buses and a plurality of liquid crystal display panel scan buses is broken, a plurality of display elements connected to the buses do not operate and display line defects occur. This display line defect is a fatal defect for the display device. If at least one of the many buses has a disconnection, the display device must be defective. The problem becomes more serious as the screen size, resolution, and definition of the liquid crystal display increases. In order to reduce the influence of the bus disconnection, there has been disclosed a precedent in which two buses transmitting the same signal are provided. As a method of arranging the buses doubly, Japanese Patent Laid-Open Publication No.
7, JP-A-56-153588 and JP-A-56-15
No. 3589.

[0007]

The effect of the bus disconnection is a serious problem particularly for a matrix type display device having a large number of display pixels. Various methods have been devised to alleviate this problem. In the above-mentioned prior example, an unnecessary bus is originally provided as an extra display device. Therefore, in a transmissive display device, there is a problem that the area of the light transmitting portion, that is, the aperture ratio is reduced and the display becomes dark. .

[0008]

According to the present invention, there is provided a display device comprising:
A display signal is transmitted to a first bus group, a scanning signal is transmitted to a second bus group, and a display unit provided corresponding to an intersection of the first bus and the second bus is determined by the two signals. A matrix-type display device to be driven, comprising: a driving circuit that applies a scanning pulse to one end of the second bus group;
A drive circuit controlled by a bus adjacent to the other end of the second bus group is formed on a substrate.

According to the present invention, with the above-described configuration, even when a specific bus has a broken portion, a controlled signal is transmitted from another bus having no break, and a correct signal is applied to each display element. You. Therefore, even if the display unit belongs to a bus having a broken portion, it is driven correctly, and as a result, the occurrence of a display line defect is suppressed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a display signal is transmitted to a first bus group, a scanning signal is transmitted to a second bus group, and the first bus and the second bus are connected to each other. A matrix-type display device for driving a display unit provided corresponding to the intersection of the buses with both signals, comprising a driving circuit for applying a scanning pulse to one end side of a second bus group; A display device characterized in that a driving circuit controlled by a bus adjacent to the other end of the bus group is formed on a substrate.

According to the above-described configuration, even when a specific bus has a broken portion, a controlled signal is transmitted from another bus having no break, and a correct signal is applied to each display element. Therefore, even if the display unit belongs to a bus having a broken portion, it is correctly driven, and as a result, the occurrence of a display line defect is suppressed. Further, since the logic circuit is formed on a substrate provided with a matrix array, the number of mounting points is reduced as compared with the case of mounting an external circuit, so that the mounting reliability can be improved and the material cost can be reduced. There is also an advantage that the display device is made thinner.

According to a second aspect of the present invention, in the first aspect of the present invention, the other end of the Nth bus of the scanning bus is N + 1 and the other end of the N + 2th bus is the same as the other end of the scanning bus. A display device including a logic circuit controlled by a logical expression f = A · B.

According to the above-described configuration, even when a specific bus has a disconnection, a controlled signal is transmitted from another bus without disconnection, and a correct signal is applied to each display element. Therefore, even if the display unit belongs to a bus having a broken portion, it is correctly driven, and as a result, the occurrence of a display line defect is suppressed.

According to a third aspect of the present invention, there is provided a display device according to the first or second aspect, wherein the logic circuit portion is constituted by a polysilicon thin film transistor. According to the configuration, even when a specific bus has a disconnection portion, a controlled signal is transmitted from another bus having no disconnection, and a correct signal is applied to each display element. Therefore, even if the display unit belongs to a bus having a broken portion, it is correctly driven, and as a result, the occurrence of a display line defect is suppressed. In addition, since the logic circuit is formed on a substrate provided with a matrix array of thin-film transistors, the number of mounting points is reduced, as compared to external circuit mounting, and there is an advantage that mounting reliability is improved and material cost is reduced. . There is also an advantage that the display device is made thinner.

According to a fourth aspect of the present invention, a display signal is transmitted to a first bus group, a scanning signal is transmitted to a second bus group, and an intersection of the first bus line and the second bus line. A matrix-type display device for driving a display unit provided in correspondence with both signals, comprising a driving circuit for applying a scanning pulse to one end side of a second bus group, and a driving circuit for applying a scanning pulse to the other end of the second bus group. At the end, a drive circuit controlled by an adjacent bus is formed on the substrate, and a disconnection of the second bus group is searched for,
A method for manufacturing a display device, comprising: disabling a drive circuit at the other end for controlling a bus having no disconnection, wherein the method described above allows a specific bus to have a disconnection even if there is a disconnection. The control signal is transmitted from the other buses, and the correct signal is applied to each display element. Therefore, even if the display unit belongs to a bus having a broken portion, it is correctly driven, and as a result, the occurrence of a display line defect is suppressed.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the driving circuit controlled by the bus adjacent to the other end of the second group of buses is constituted by a polysilicon thin film transistor. A method for manufacturing a display device, characterized in that, by the above-described method, even when a specific bus has a broken portion, a signal controlled from another bus without a break is transmitted to each display element. Is a correct signal. Therefore, even if the display unit belongs to a bus having a broken portion, it is correctly driven, and as a result, the occurrence of a display line defect is suppressed.

(Embodiment 1) FIG. 1 shows a schematic configuration of a liquid crystal display device according to an embodiment of the present invention. In FIG.
1 is a liquid crystal display panel, 2 is a source bus driving circuit, 3 is a scanning bus driving circuit, 4 is a liquid crystal display, and 5 is a control driving circuit.

The present invention is different from the prior art in that a source bus driving circuit 2, which is a part of a driving circuit for applying a display signal and a scanning signal to a liquid crystal display panel 1, respectively,
The point is that a control circuit section 5 for connecting the scanning buses is simultaneously formed on the other end side of the scanning bus driving circuit section in addition to the scanning bus driving circuit section 3.

FIG. 2 shows a detailed configuration of the control drive circuit section 5 of FIG. In FIG. 2, logic circuits 23a, 23b, 23c, 23d and the like controlled by scanning buses V1, V2, V3,..., Vn are simultaneously formed on the other end side of the scanning bus driving circuit.

The other end of the scanning bus Vn (the control drive circuit section 23) is controlled by a logic circuit having a logical expression f = A.B with adjacent scanning buses Vn + 1 and Vn + 2.

FIG. 3 shows the logic function of the logic circuit shown in FIG. FIG. 4 shows a timing chart of signal waveforms in the device of this embodiment.

In FIG. 4, V1, V2, and V3 are input signals from the scanning bus driving circuit portion of the scanning buses V1, V2, and V3 shown in FIG. 2, respectively, and V1 'is a signal from the logic circuit 23a of the control driving circuit portion. The output signal is shown.

For example, when there is a bus disconnection at point A of the scanning bus V1 shown in FIG. 2, the scanning signal V1 input from the scanning bus driving circuit section during the selection period T1 is displayed on the display elements 30b and 30c before the point A. .. Are not transmitted. However, paying attention to the next selection period T2, at this time, the bus V2 is at level 1 and V3 is at level 0, and this value becomes the input value of the logic circuit 23a and the output value connected to the other end of V1. f1 becomes 1 level. Therefore, even if there is one disconnection a in the scanning bus V1, the scanning signal V1 'is transmitted from V2 and V3 via 32a, and the corresponding display signal is transmitted to the display elements 30b, 30c. In the next selection period T3, the output signal of 23a becomes 0. Therefore, the scanning pulse is applied regardless of the presence / absence of a disconnection (but one location) in the scanning signal bus V1 and without inputting an external signal other than the scanning signal.

Also, as shown in FIG.
2, V3, V4, V5, and V6 have no bus disconnection, and therefore, logic circuits 23b, 23c, 2
By cutting off the signal output part 3d by a razor, the logic circuit was disabled.

Next, an example of the manufacturing method will be described with reference to FIG. FIG. 5 is a cross-sectional view at each stage of the manufacturing process of the polysilicon thin film transistor constituting the liquid crystal display panel built-in drive circuit. First, a base insulating film 11 made of a material such as SiO2 is formed on a glass substrate 10 made of a translucent glass having a strain point of 670 ° C. by a method such as a normal pressure CVD method at a temperature condition of 450 ° C. . The thickness of the base insulating film 11 is, for example, 2000A.

After forming the base insulating film 11, a-Si:
A semiconductor material film 12 of H (compound of amorphous silicon and hydrogen) is formed to a predetermined thickness (for example, 500 A) by a method such as plasma CVD, and is further patterned into a predetermined shape by a lithography process. I do. Predetermined conditions for the patterned semiconductor material film 12 (for example, processing temperature 450 ° C., processing time 60 minutes)
Dehydrogenation treatment. This step aims at preventing generation of ablation of the semiconductor material film 12 due to desorption of hydrogen during crystallization.

After the dehydrogenation, the semiconductor material film 12 is crystallized by a technique such as irradiation with a XeCl excimer laser having a wavelength of 380 nm, thereby turning the semiconductor material film 12 into a p-Si semiconductor layer 12 (see FIG. 5A). ).

Next, a gate oxide film 13 made of, for example, SiO 2 is formed on the semiconductor layer 12 to a very thin film thickness of, for example, 1000 A by a technique such as a normal pressure CVD method at a temperature of 450 ° C. After the gate oxide film 13 is formed,
The conductor film 14 made of Al or the like is formed to a predetermined thickness (for example, 30
00A) is formed by a technique such as sputtering. Then, the conductor film 14 is patterned into a predetermined shape by a lithography process using an Al etching solution, and thereby the conductor film 14 is used as the gate electrode 14 (see FIG. 5B).

Next, impurities such as phosphorus and boron are implanted into ions on both sides of the semiconductor layer 12 by using the gate electrode 14 as a mask by a technique such as an ion doping method (self-aligned structure). As a result, in the semiconductor layer 12, a channel region 12a is formed at the center and the channel region 12a is formed.
A source region 12b and a drain region 12c are respectively formed on both sides of “a” (see FIG. 5C).

Next, an interlayer insulating layer 15 made of SiO 2 or the like is formed on the gate oxide film 13 by a predetermined thickness (for example, 4000).
A), the gate electrode 14 is covered with the formed interlayer insulating film 15. The interlayer insulating film 15 is, for example, 45
A film is formed by a normal pressure CVD method at a temperature of 0 ° C. (FIG. 5)
(D)).

Next, the interlayer insulating film 15 and the gate insulating film 13
Then, the source region 12 is formed by using a lithography process.
b, contact hole 16 reaching drain region 12c
To form After the contact holes 16 are formed, a conductive film 17 made of a laminate of two types of conductors such as a Ti film and an Al film is formed on the interlayer insulating film 15. The conductive film 17 is formed by, for example, sputtering. The thickness of the Ti film is, for example, 1000 A, and the thickness of the Al film is, for example, 7000 A. The contact hole 16 is completely filled with the conductive film 17 thus formed. Furthermore, the source / drain electrodes 17 are formed by patterning the conductive film 17 into a predetermined shape in a lithography process using a BCl3 Cl2 gas (see FIG. 5E).

Next, a passivation film 18 serving as a protection film
Is formed. Subsequently, at a processing temperature of 350 ° C., a deuterium gas flow rate of 300 sccm, and an RF power of 800 W, 2
Perform plasma hydrogenation for a long time. Finally, in a lithography process, the passivation film 18 is patterned in a predetermined shape, thereby completing a thin film transistor constituting a built-in drive circuit portion.

In the embodiment of the present invention, the case of the low-temperature p-Si thin film transistor has been described. However, other monocrystalline and polycrystalline semiconductor materials can be used.

The TFTs forming the matrix of the liquid crystal display section 31 are a-Si TFTs, and the TFTs forming the built-in circuit section are TFTs.
A TF in which the display unit and the built-in drive circuit units 20, 21, and 23 are made of different materials, such as a low-temperature p-Si TFT
It can also be composed of T.

[0035]

As described above, according to the present invention, the display signal is transmitted to the first bus group, the scanning signal is transmitted to the second bus group, and the first bus and the second bus are connected. Even if there is a break in a specific bus, a signal controlled from another bus without a break is transmitted by the two signals to the display unit provided corresponding to the intersection, and a signal is applied to each display element. You. As a result, generation of display line defects is suppressed.

As described above, the yield of the display device is remarkably improved, and even if the display unit belongs to a bus having a broken portion, it can be correctly driven, and the display device can be provided at a low cost and in large quantities. It is to be.

Further, according to one embodiment of the present invention, the logic circuit is formed in a very fine area on the substrate provided with the matrix array of the low-temperature p-Si thin film transistors, so that other than the display signal and the scanning signal, Since there is no need to input an external input signal, the number of mounting points is reduced as compared with the mounting of an external circuit, and there are advantages in that mounting reliability is improved and material cost is reduced. There is also an advantage that the display device is made thinner.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a control drive circuit portion and a logic circuit of the liquid crystal display device according to the embodiment of the present invention.

FIG. 3 is a diagram showing a logical function of a logic circuit of the liquid crystal display device according to the embodiment of the present invention.

FIG. 4 is a timing chart of a signal waveform of a liquid crystal display device according to an embodiment of the present invention.

FIG. 5 is a sectional view showing a manufacturing process of the p-Si TFT according to the embodiment of the present invention.

FIG. 6 is a conceptual diagram of a conventional p-Si TFT liquid crystal display device.

FIG. 7 is an electrical block diagram of a source bus driving circuit unit 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal display panel 2 Source bus drive circuit 3 Scanning bus drive circuit 4 Liquid crystal display 5 Control drive circuit

Claims (5)

[Claims] A display unit is provided for transmitting a display signal to a first bus group, transmitting a scan signal to a second bus group, and corresponding to an intersection of the first bus and the second bus. A drive circuit for applying a scanning pulse to one end of the second bus group, and a bus adjacent to the other end of the second bus group. A driving circuit controlled by the driving circuit is formed on a substrate. 2. The other end of the Nth bus of the scanning bus is N +
2. The display device according to claim 1, further comprising a logic circuit controlled by the other end of the (1, N + 2) th bus and a logical expression f = AB. 3. The driving circuit controlled by a bus adjacent to the other end of the second group of buses comprises a polysilicon thin film transistor.
The display device according to claim 1. 4. A display unit which transmits a display signal to a first group of buses, transmits a scanning signal to a second group of buses, and is provided corresponding to an intersection of the first and second buses. A matrix-type display device, which is driven by the two signals, further comprising a driving circuit for applying a scanning pulse to one end of the second bus group, the driving circuit being adjacent to the other end of the second bus group. A drive circuit controlled by a bus is formed on the substrate, and a disconnection of the second bus group is searched, and a drive circuit at the other end for controlling a bus having no disconnection is disabled. Manufacturing method of a display device. 5. The method according to claim 4, wherein the driving circuit controlled by a bus adjacent to the other end of the second group of buses comprises a polysilicon thin film transistor.