JPH06202138A - Liquid crystal display - Google Patents

Abstract

PURPOSE:To improve display quality by preventing luminance difference between the upper and lover screen sides by connecting the input wiring of each semicon ductor device for driving the upper screen and lover screen together at a posi tion far from a power source input part. CONSTITUTION:Since input lines 6a, 6b are wired counterclockwise after being inputted from a flexible printed board 5 on the right side, the line resistance value of wiring is gradually increased as advancing the left side, and potential is gradually decreased, however, when the input lines 6a, 6b with different film thickness and width are provided, difference in the decreasing state of the potential occurs, and the potential difference between the lines 6a, 6b is increased as advancing the left side when no connection line 6C is provided. Therefore, no luminance difference occurs at a right side part A near to the substrate 5 of the upper screen 3a and that of the lower screen 3b, however, it occurs at a part C at the left side from a part B in the center. However, since the left terminals of the lines 6a, 6b are connected mutually with the connection line 6C, the potential difference at the left terminals of the lines 6a, 6b can be eliminated, which prevents the luminance difference from occurring.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In a liquid crystal display device of a multiplex drive, which is one of time-division drive, a display area may be divided into upper and lower parts, and the number of horizontal lines can be scanned in one field. It is possible to improve the display quality such as contrast by reducing the half.

However, the two components of the liquid crystal display device are
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 for the upper screen and the lower screen I
C and the wiring pattern to this are independent in the upper and lower sides, and if the resistance values of the input wirings up to the driving IC are different in the upper and lower sides, a difference in brightness occurs between the upper and lower screens. Also, in a tab type liquid crystal display device in which a signal is input from the driving IC to the display unit using a flexible printed circuit board, and in a zebra rubber type liquid crystal display device in which a signal input from the driving IC to the display unit is performed using zebra rubber. When driving is divided into two vertically, if the wiring resistance from the power input unit to the driving IC is different at the top and bottom, a difference in brightness occurs at the top and bottom of the screen.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of these problems, and an object thereof is to prevent a difference in luminance between upper and lower screens.

[0005]

In order to solve the above problems, according to the present invention, the input wirings of the driving semiconductor elements for the upper screen and the lower screen are connected to each other at a position far from the power input section. ing. In this case, if the logic GND of the driving semiconductor element and / or the input wiring of the driving power supply GND are connected to each other, a good result can be obtained relatively easily.

[0006]

[Function] When there is a difference in the resistance of the input wiring, the potential difference also increases at a position far from the power supply input section, but by connecting them to each other, the potential difference disappears, and a difference in brightness occurs between the upper and lower screens. Is eliminated.

[0007]

EXAMPLE Next, one example shown in the figure will be described. FIG. 1 is a plan view of a COG type liquid crystal display device, in which 1 is a glass substrate on the segment side and 2 is a glass substrate on the common side having a smaller area than this, and a liquid crystal is sealed between them to form a display area. 3 is formed. 4a is a driving IC mounted on the upper side edge of the glass substrate 1, 4b is a driving IC mounted on the lower side edge of the glass substrate 1, and 5 is a flexible print connected to the right side of the glass substrate 1. A substrate, 6a is an input line for the driving IC 4a formed from the flexible printed circuit board 5 along the upper edge of the glass substrate 1, and 6b is a driving circuit formed from the flexible printed circuit board 5 along the lower edge of the glass substrate 1. The input line 6c for the IC 4b is a connection line formed along the left side edge of the glass substrate 1 and connecting the corresponding left ends of the input lines 6a and 6b to each other.

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 section via the input lines 6a and 6b, respectively, and displayed. The area 3 is divided into an upper screen 3a and a lower screen 3b so that two screens can be displayed. Although each of the input lines 6a and 6b actually has 10 or more upper and lower lines, two lines are shown in a simplified manner in order to avoid complication.

Here, since the input lines 6a and 6b enter from the flexible printed board 5 on the right side and are routed to the left, the total resistance value of the wiring gradually increases toward the left side, and the potential thereof becomes higher. It gradually decreases, but temporarily each input line 6
When the film thicknesses and widths of a and 6b are different, a difference in potential lowering state occurs, and when there is no connecting line 6c, the potential difference between both input lines 6a and 6b increases toward the left side. Therefore, there is almost no difference in brightness between the upper screen 3a and the lower screen 3b on the right-hand side closest to the flexible printed circuit board 5, that is, the part indicated by A in the display area 3, but the left side from the part indicated by B in the center. The luminance difference appears in the portion indicated by C, and the luminance difference appears more conspicuously 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 brightness as described above can be eliminated. It is prevented from occurring.

The input lines 6a and 6b are patterned by a generally performed thin film etching, and the connection line 6c is 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 the case where the wiring is formed by another method.

In this way, each of the input lines 6a,
Since the left ends of 6b are connected to each other to eliminate the potential difference between both input lines, the effect becomes smaller when the resistance value of the connection line 6c is high. Also, it is not necessary to connect all of the upper and lower input lines to each other, and connecting the GND line is most effective. Especially, GND for logic and drive power
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 visual evaluation of the brightness difference when the resistance value of the connection line 6c is changed when the upper and lower logic GNDs and the drive power supply GND are respectively connected, and practically 10Ω or less, It seems that about 5Ω or less is preferable.

[0012]

[Table 1]

[0013]

As is apparent from the above-described embodiments, the present invention is a liquid crystal display device in which a display region is vertically divided into two parts and is driven, and in each of the driving semiconductor elements for the upper screen and the lower screen. The input wires are connected to each other at a position far from the power input section. Therefore, even if there is a difference in the resistance of the input wires for the upper screen and the lower screen, the potential difference will not occur due to the interconnection, and the brightness difference between the upper and lower screens can be prevented and the display quality can be improved. . In particular, by connecting at least one of the logic GND and the drive power GND of the driving semiconductor element, the effect of the present invention can be exhibited relatively easily to eliminate the brightness difference.

[Brief description of 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

Claims (1)

[Claims] 1. A liquid crystal display device in which a display area is divided into upper and lower parts and driven, and input wirings of respective driving semiconductor elements for an upper screen and a lower screen are connected to each other at a position far from a power supply input section. A liquid crystal display device characterized by the above.