JP3188778B2 - Liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to an improvement in a liquid crystal display device that is driven separately.

[0002]

2. Description of the Related Art A multiplex driving liquid crystal display device, which is one of the time-division driving methods, is driven by dividing a display area into upper and lower parts. Is reduced by half, the display quality such as contrast can be improved.

However, the liquid crystal display device 2
In the case of a so-called COG type liquid crystal display device in which a semiconductor element such as a driving IC is mounted on one of the glass substrates and connected to a wiring pattern, each driving I / O for the upper screen and the lower screen is used.
C and its wiring pattern are independent at the top and bottom, respectively. If the resistance of the input wiring to the driving IC differs between the top and bottom, a difference in brightness occurs between the upper and lower screens. Also, a tab-type liquid crystal display device in which signal input from the driving IC to the display unit is performed on a flexible printed circuit board, and a zebra rubber type liquid crystal display device in which signal input from the driving IC to the display unit is performed using zebra rubber. In the case where the wiring is divided into upper and lower parts, if the wiring resistance from the power supply input section to the driving IC is different between the upper and lower parts, a difference in luminance occurs between the upper and lower parts of the screen.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem and has an object to prevent a difference in luminance between upper and lower screens.

[0005]

In order to solve the above-mentioned problems, according to the present invention, a liquid crystal is sealed between a large area substrate and a small area substrate to form a rectangular display area. The display area is divided into upper and lower parts, and a driving semiconductor element for the upper screen of the display area is mounted on the upper side edge of the large-area substrate, and a lower side edge of the display area is used for driving the lower screen. A semiconductor element is mounted, and a power input portion is further provided on one of the left and right side edges, and an input wiring connecting this power input portion and each of the driving semiconductor elements for the upper screen and the lower screen is provided on a large area substrate. In the liquid crystal display device formed on the upper and lower side edges of the liquid crystal display to drive the display area, at least one of the logic wiring GND and the driving power supply GND among the input wirings is connected to the left and right sides of a large-area substrate. Connection with a resistance of 10Ω or less at the other side edge of They are connected to each other by.

[0006]

When there is a difference in the resistance of the input wiring, the potential difference increases at a position far from the power supply input portion. However, at least one of the logic GND and the driving power supply GND of the input wiring is connected with a resistance of 10Ω or less. The potential difference is eliminated by connecting to each other by the line, and it is relatively easy to eliminate the difference in luminance between the upper and lower screens.

[0007]

Next, one embodiment shown in the drawings will be described. FIG. 1 is a plan view of a COG type liquid crystal display device, wherein 1 is a segment-side glass substrate, 2 is a common-side glass substrate having a smaller area than this, and a liquid crystal is sealed between these, and a display area is provided. 3 are formed. Reference numeral 4a denotes a driving IC mounted on the upper side edge of the glass substrate 1, 4b denotes a driving IC mounted on the lower side edge of the glass substrate 1, and 5 denotes a flexible print connected to the right side of the glass substrate 1. Substrate, 6a is an input line for driving IC 4a formed along the upper edge of flexible printed circuit board 5 from glass substrate 1, and 6b is a drive line formed along the lower edge of flexible printed circuit board 5 along glass substrate 1. The input line 6c for the IC 4b is a connection line formed along the left edge of the glass substrate 1 and interconnecting the corresponding left ends of the input lines 6a and 6b.

In this embodiment, the driving ICs 4a and 4b are supplied with driving power and signals from the flexible printed circuit board 5, which is a power input unit, via input lines 6a and 6b. The area 3 is divided into an upper screen 3a and a lower screen 3b, and two-screen display is performed. It should be noted that each of the input lines 6a and 6b actually has approximately 10 or more upper and lower lines, but in the drawing, two lines are shown in a simplified manner to avoid complication.

Since each of the input lines 6a and 6b enters from the flexible printed circuit board 5 on the right side and is routed leftward, the total resistance value of the wiring gradually increases toward the left side, and the potential thereof increases. Although it gradually decreases, if each input line 6
If the thicknesses and widths of a and 6b are different, there is a difference in the state of potential drop. If there is no connection line 6c, the potential difference between the input lines 6a and 6b increases toward the left side. For this reason, the brightness difference hardly occurs in the right portion of the upper screen 3 a and the lower screen 3 b closest to the flexible printed circuit board 5, that is, in the portion indicated by A in the display area 3, but leftward from the central portion indicated by B. In the portion indicated by C, a luminance difference appears, and the luminance difference becomes more noticeable toward the left side. However, in this embodiment, since the left ends of the input lines 6a and 6b are connected to each other by the connection line 6c, the potential difference at the left ends of the input lines 6a and 6b can be eliminated, and the difference in luminance as described above can be reduced. It is prevented from happening.

Each of the input lines 6a and 6b is patterned by etching of a thin film which is generally performed, and the connection lines 6c are also patterned at the same time as the input lines 6a and 6b. The present invention is not limited to this, and the present invention can be applied to a case where the wiring is formed by another method.

As described above, each input line 6a, 6a,
Since the left ends of the connection lines 6b are connected to each other to eliminate the potential difference between the two input lines, the effect is reduced if the resistance value of the connection line 6c is high. Also, it is not necessary to connect all of the many upper and lower input lines to each other, and it is most effective to connect the GND lines, especially to the GND for the logic and the GND for the driving power supply.
It has been found that good results can be obtained relatively easily by connecting at least one of the two lines. Table 1 below
Shows the result of visually evaluating the luminance difference when the resistance value of the connection line 6c is changed when the upper and lower logic GNDs and the driving power supply GND are connected, respectively. It seems that it is preferable to set the resistance to about 5Ω or less.

[0012]

[Table 1]

[0013]

As is apparent from the above embodiment, the present invention divides a display area formed by enclosing liquid crystal between a large-sized substrate and a small-sized substrate into two upper and lower regions, and A driving semiconductor element for the upper screen of the display area is mounted on the upper side edge of the substrate having an area, and a driving semiconductor element for the lower screen of the display area is mounted on the lower side edge. The input wiring for connecting between the power supply input unit provided in each of the above and the driving semiconductor elements for the upper screen and the lower screen is formed on the upper and lower side edges of the large-area substrate, respectively, to drive the display area. In the liquid crystal display device described above, at least one of the logic GND and the driving power GND among the input wirings is connected to each other by a connection line having a resistance value of 10Ω or less at the other of the left and right side edges of the large-area substrate. It is something to do. Therefore, even if there is a difference between the resistance of the input wiring for the upper screen and the resistance of the input wiring for the lower screen, a potential difference is not generated due to the interconnection, and the luminance difference between the upper and lower screens is relatively easily prevented to improve the display quality. can do.

[Brief description of the drawings]

FIG. 1 is a plan view of an embodiment of the present invention.

[Explanation of symbols]

 1, 2 glass substrate 3 display area 3a upper screen 3b lower screen 4a, 4b driving IC 5 flexible printed circuit board 6a, 6b input line 6c connection line

Continuation of front page (56) References JP-A-2-90126 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/1345 G02F 1/133 545 G09G 3/36

Claims (1)

(57) [Claims] A liquid crystal is sealed between a large-area substrate and a small-area substrate to form a rectangular display area, and this display area is divided into two parts, an upper side and a lower side. Along with mounting a driving semiconductor element for the upper screen of the display area on the edge,
On the lower side edge, a drive semiconductor element for the lower screen of the display area is mounted, and further, a power input unit is provided on one of the left and right side edges,
The input wiring connecting between the power input section and the driving semiconductor element for the upper screen and the input wiring connecting the power input section and the driving semiconductor element for the lower screen are connected to the upper and lower sides of a large-area substrate. In the liquid crystal display device formed on each of the side edges to drive the display area, at least one of the logic wiring GND and the driving power supply GND among the input wirings is connected to the left and right side edges of a large-area substrate. On the other hand, the liquid crystal display device is connected to each other by a connection line having a resistance value of 10Ω or less.