JPH0792479A - Display device - Google Patents

Abstract

(57) [Summary] [Object] The present invention mounts a plurality of driver ICs for driving the display unit on a substrate on which the display unit is provided, and uses a common wiring formed on the substrate to provide the plurality of the driver ICs. In a display device in which all or part of the driver ICs are driven, it is intended to reduce the difference in wiring resistance between the driver ICs for driving and obtain good display quality without increasing cost or reducing screen size. . [Configuration] Scan signal driver I on the lower substrate 1
C3a and 3b are mounted, and power and input signals are externally supplied from the FPC 12 via the common wirings 5 and 6 provided on the lower substrate 1. At this time, the arrangement pitch of the driver ICs is made smaller than the width Wy of the display area in charge of the scanning signal driver ICs 3a and 3b. Further, the scanning signal driver ICs 3a and 3b are connected to the input section 13 of the common wiring.
Place it close to.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driver IC mounting mode of a display device, particularly a flat panel display device such as a liquid crystal display device.

[0002]

2. Description of the Related Art A liquid crystal display device will be described below as an example. As a driver IC mounting method for a liquid crystal display device, a COG in which a driver IC for direct drive is mounted on a display substrate
The (chip-on-glass) method is drawing attention because of its low cost, compactness, and high environmental resistance.

In the COG method, recently, in order to further improve its low cost and compactness, a method of driving a plurality of driver ICs by a thin film common wiring formed on a substrate has been adopted. There is. When a plurality of driver ICs are arranged so as to be driven by this common wiring, the driver IC is conventionally equal to the width of the display area in charge of the driver IC, as shown in the embodiment of JP-A-4-120517. They are arranged at a pitch higher than that.

Hereinafter, an example of the prior art will be described in more detail using the liquid crystal display device shown in FIG. In FIG.
Scanning signal driver ICs 23a and 23b and image signal driver ICs 24a to 24d are mounted on the lower substrate 21 by a COG mounting method. These driver ICs have an FPC3 connected to the end of the lower substrate 21.
2 supplies power and input signals via thin film wirings 25, 26, 27 and 28 formed on the lower substrate 21, of which the thin film wirings 25 and 26 serve as common wirings for scanning signal drivers. Power and input signals are supplied to both the ICs 23a and 23b.

Now, in such a liquid crystal display device,
Conventionally, as shown in FIG. 3, as shown in FIG.
a and 23b are arranged at the center of the extension of the display area in charge of each, and the arrangement pitch of the scanning signal driver ICs 23a and 23b is equal to the width Wy of the display area.

[0006]

In this case, the scan signal driver ICs 23a and 23b are provided with common wirings 25, 2
6, a wiring resistance difference corresponding to the length of the width Wy of the display area is generated. Specifically, in the liquid crystal display device shown in FIG. 3, the scan signal driver IC 23 is used.
The distance between a and 23b is 40 mm, and the surface resistance 2
When a wiring having a width of 0.5 mm is formed with a wiring material of ohm / □, the wiring resistance difference between the scanning signal driver ICs 23a and 23b is 160 ohms.

On the other hand, in this liquid crystal display device, in the scanning signal driver ICs 23a and 23b, when there is a difference of 100 ohms or more in the input portion resistance of the Vee power supply terminal, the contrast is displayed in the display area in charge of the scanning signal driver ICs 23a and 23b. It is known to make a difference. Therefore, the above-mentioned difference in contrast is caused by the above-mentioned difference in wiring resistance.

In the liquid crystal display device shown in FIG. 3, the distance from the input portion 33 of the common wiring provided at the end of the lower substrate 21 to the scanning signal driver IC 23a is 30 mm.
When a wiring having a width of 1 mm is formed by the same wiring material, the wiring resistance between them is 60 ohms, and the wiring resistance between the scanning signal driver ICs 23a and 23b is 80.
The wiring resistance from the input section 33 of the common wiring to the scanning signal driver IC 23b is 140 ohms, which is the sum of the two. On the other hand, a scanning signal driver IC
It has been found that 23a and 23b cause a logic malfunction when a resistance of 150 ohms is added to the input part of the Vdd power supply terminal. That is, in this case, the margin of the wiring resistance until the logic malfunction of the scanning signal driver IC 23b is only 10 ohms, and the logic malfunction occurs when the specific resistance and the film thickness of the wiring material vary due to the process variation. I'm afraid. As described above, when the common wiring is formed by the above-described design, a contrast difference may occur in the display areas handled by the scanning signal driver ICs 23a and 23b, and a logic malfunction may occur in the scanning signal driver IC 23b. It will be big.

Conventionally, in order to avoid this, a method has been taken in which a low resistance wiring material is newly added to reduce the surface resistance of the wiring, or a wiring width is expanded to reduce the wiring resistance. In the former case, there is a problem that the cost increases due to the addition of wiring material, and in the latter case, the screen size is reduced by expanding the formation area of the common wiring, or the number of large boards is taken to secure the screen size. Then, there was a problem of increasing costs.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a display device which can obtain good display quality without reducing the screen size and increasing the cost.

[0011]

In order to achieve the above object, the present invention arranges a plurality of driver ICs driven by common wiring at a pitch narrower than the width of the display area in charge thereof.

It is desirable that the pitch be 1/2 or less of the width of the display area. Further, it is desirable that a plurality of driver IC groups driven by the common wiring are arranged close to the side of the external signal input unit to the common wiring.

[0013]

By arranging as described above, it is possible to reduce the wiring resistance difference between the driver ICs caused by the common wiring, and it is possible to obtain a good display quality with no contrast difference between the display areas. .

Further, it is possible to obtain a sufficient margin that does not cause a logic malfunction with respect to the process variation, and it is possible to improve the yield rate.

[0015]

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

FIG. 1 shows a matrisk type display device which is an embodiment of the present invention. Scanning signal driver ICs 3a and 3b and image signal driver ICs 4a to 4d are mounted on the lower substrate 1 by a COG mounting method. Power and input signals are supplied from the FPC 12 to these driver ICs through thin film wirings 5, 6, 7, and 8 formed on the lower substrate.

The image signal driver ICs 4a to 4d are
Since the power source and the input signal are supplied by the thin film wirings 7 and 8 having the same length, no difference in resistance occurs between the driver ICs and no difference in display state occurs. Therefore, the driver ICs are arranged so as to be positioned in the center of the display area in which each driver IC is in charge, and the arrangement pitch is set to be equal to the width Wx of the display area of the image signal driver IC, as is usually done. On the other hand, the scanning signal driver ICs 3a and 3b share the thin film wirings 5 and 6.

Power and signals are externally supplied to the thin film wirings 5, 6, 7, and 8 from an FPC 12 connected to an end of the lower substrate 1.

The thin film wirings 5, 6, 7 and 8 are Ta,
It has a laminated structure of Ti and ITO, and its surface resistance is 2 ohm / □ as a design value. The thin film wiring 5 is a Vee power supply wiring for the scanning signal driver ICs 3a and 3b, and its width is 0.5 mm, and the thin film wiring 6 is a scanning signal driver IC.
3a, 3b Vdd power supply wiring, and its width is 1 mm. The width Wy of the display area of the scanning signal driver ICs 3a and 3b is 40 mm, the distance from the common wiring input section 13 to the scanning signal driver IC 3a is 40 mm, and the distance between the scanning signal driver ICs 3a and 3b is the width of the display area. It is 20 mm, which is 1/2 of Wy. This allows
The wiring resistance difference between the scanning signal driver ICs 3a and 3b is 80 ohms, and a resistance difference of 10 which causes a contrast difference is obtained.
It is below 0 ohms. Also, the common wire input unit 13
Wiring resistance from the scan signal driver IC 3a to 8
0 ohm, scan signal driver ICs 3a, 3b
A wiring resistance of 40 ohms is added between the common wiring input section 13
Wiring resistance from 1 to scanning signal driver IC 3b is 1
Since the resistance is 20 ohms, it is below the additional resistance of 150 ohms which causes a logic malfunction, and has a margin of 30 ohms. In this way, it was possible to obtain a liquid crystal display device with good display quality and with a margin against process variations.

FIG. 2 shows a second embodiment of the present invention. In the liquid crystal display device of this embodiment, the scanning signal driver I
Both C3a and 3b are brought close to the input section 13 side of the common wiring. Specifically, the distance from the input section 13 of the common wiring to the scanning signal driver IC 3a is 20 mm, and the distance between the scanning signal driver ICs 3a and 3b is 20 mm, which is the same as in the above-described embodiment. As a result, the wiring resistance from the input section 13 of the common wiring to the scanning signal driver IC 3a becomes 40 ohms, and the scanning signal driver IC 3a
A wiring resistance of 40 ohms between 3a and 3b is added, and the wiring resistance from the input portion 13 of the common wiring to the scanning signal driver IC 3b is 80 ohms, which is much lower than the additional resistance of 150 ohms which causes a logic malfunction and is 70 ohms. Will have a margin. In this way, it was possible to obtain a liquid crystal display device with a further increased margin against process variations.

Further, in the present embodiment, the present invention is applied only to the arrangement of the scanning signal driver ICs, but it is also applicable to the case where the image signal driver ICs are driven by the common wiring.

Further, in this embodiment, two drivers I
Although the present invention is applied to the C array, it can also be applied to an array of three or more driver ICs.

[0023]

As described above, by applying the present invention, it is possible to reduce the wiring resistance difference between the driver ICs caused by the common wiring, and to obtain a good display quality with no contrast difference between the display areas. It becomes possible to obtain.

Further, it is possible to obtain a sufficient margin that does not cause a logic malfunction with respect to the process variation, and it is possible to improve the yield rate.

[Brief description of drawings]

FIG. 1 is a plan view of a liquid crystal display device showing an embodiment of the present invention.

FIG. 2 is a plan view of a liquid crystal display device showing another embodiment of the present invention.

FIG. 3 is a plan view of a liquid crystal display device showing an embodiment of the prior art.

[Explanation of symbols]

1, 21 Lower substrate 2, 22 Upper substrate 3a, 3b, 23a, 23b Scan signal driver I
C 4a, 4b, 4c, 4d, 24a, 24b, 24c, 2
4d Image signal driver IC 5, 6, 25, 26 Common thin film wiring for scanning signal driver IC 7, 8, 27, 28 Thin film wiring for image signal driver IC 11, 31 Display area 12, 32 FPC 13, 33 Input Part Wy Scan signal driver IC display area width Wx Image signal driver IC display area width

Claims (3)

[Claims] 1. A plurality of driver ICs for driving the display unit are mounted on a substrate on which the display unit is provided, and a common wiring formed on the substrate allows all or a part of the plurality of driver ICs. In the display device for driving the display device, a plurality of driver ICs driven by the common wiring are arranged at a pitch narrower than the width of the display area in charge thereof. 2. The display device according to claim 1, wherein an array pitch of a plurality of driver ICs driven by the common wiring is ½ or less of a width of a display area in charge of the driver ICs. . 3. The display device according to claim 1, wherein a plurality of driver IC groups driven by the common wiring are arranged close to an external signal input section side to the common wiring.