JP3110339B2 - Wiring method of driving power supply line of liquid crystal display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of wiring a driving power supply line of a liquid crystal display device used as a display of an information device such as a video device or a computer.

[0002]

2. Description of the Related Art FIG. 8 shows a configuration of a liquid crystal display device employing a conventional driving power supply line wiring method. In this liquid crystal display device, as shown in FIG.
The signal line 11 divided into two parts above and below the center of the display area
And the scanning lines 12 are arranged in a matrix, and a pixel electrode 13 is formed and arranged at the intersection. The liquid crystal panel 14 includes a signal line driving circuit 15 and a scanning line driving circuit 16.
And is driven by A plurality of signal line driving circuits 15 and scanning line driving circuits 16 are arranged around the liquid crystal panel 14 according to the number of signal lines and the number of scanning lines. In the liquid crystal panel 14 of FIG. 8, the number of signal lines 11 is M and the number of scanning lines 12 is 2N.

A signal line driving circuit 15 is disposed above and below a liquid crystal panel 14 to perform upper and lower two-division driving for driving the signal line 11 by dividing it vertically. Since the signal line drive circuits 15 are arranged vertically, the drive power supply input terminals of each signal line drive circuit 15 are arranged to be vertically symmetrical.

The upper and lower signal line driving circuits 15 are referred to as an upper signal line driving circuit and a lower signal line driving circuit. The drive power supply voltage of the signal line drive circuit 15 is VH and VL, and is supplied from the liquid crystal drive power supply circuit 17 through a drive power supply line (not shown) for the signal line 11. The drive power supply line for this signal line 11 is composed of a VH drive power supply line 24 and a VL drive power supply line 23 corresponding to the drive power supply voltages VH and VL, and a lower VH drive power supply corresponding to the upper and lower signal line drive circuits 15. Line 19, lower VL
It branches into a drive power supply line 20, an upper VH drive power supply line 21, and an upper VL drive power supply line 22. The driving power supply voltage of the scanning line driving circuit 16 is supplied from the liquid crystal driving power supply circuit 17 through the scanning line driving power supply line 18.

The upper and lower VH drive power supply lines 21, 19 and V
The resistance from each branch point of the L drive power supply lines 22 and 20 to each terminal point is defined as a wiring resistance. In the conventional wiring method of the driving power supply lines of the liquid crystal display device shown in FIG. 8, the wiring length of the upper driving power supply lines 21 and 22 of the VH and VL is smaller than that of the lower driving power supply lines 19 and 2.
The wiring length of the upper drive power supply lines 21 and 22 is different from that of the lower drive power supply lines 19 and 20. The wiring resistance of the upper drive power supply lines 21 and 22 is larger than the wiring resistance of the lower drive power supply lines 19 and 20. Here, the current flowing through the signal line drive power supply line is referred to as a drive power supply line current.

When the driving voltages of the upper and lower signal lines 11 of the liquid crystal panel 14 are the same, for example, in the case of full screen white, black, red, etc., in which the upper and lower screens of the upper and lower screens display exactly the same image, The upper drive power supply line current and the lower drive power supply line current are the same. However, since the wiring resistances of the upper drive power supply lines 21 and 22 and the lower drive power supply lines 19 and 20 are different, the voltage drop due to the drive power supply line current and the wiring resistance differs in the upper and lower drive power supply lines 21, 22, 19 and 20. . In FIG. 8, the voltage drops of the upper drive power supply lines 21 and 22 correspond to the lower drive power supply lines 19 and
It becomes larger than the voltage drop of 20. Therefore, VH and VL input to the upper signal line drive circuit 15 are different from VH and VL input to the lower signal line drive circuit 15. The difference is a wiring resistance difference between the upper and lower drive power supply lines 21, 22, 19, and 20, and a voltage drop difference due to the drive power supply line current.

The wiring resistance of the upper VH driving power supply line 21 is R _uh , the wiring resistance of the upper VL driving power supply line 22 is R _ul , and the lower V
The wiring resistance of the H drive power supply line 19 is R _lh , the wiring resistance of the lower VL drive power supply line 20 is R _ll , the drive power supply line current is i, and VH and VL of the upper signal line drive circuit 15 are VH (upper), VL
Assuming that VH and VL of the (upper) and lower signal line drive circuits 15 are VH (lower) and VL (lower), each voltage drop due to the wiring resistance and the drive power supply line current is expressed by Equation 1.

[0008]

(Equation 1)

Therefore, the driving voltage (signal line driving voltage) for the signal lines 11 of the liquid crystal panel 14 is different between the upper screen and the lower screen of the upper and lower two-part drive, as can be seen from the equation (1). Therefore, a difference corresponding to Equation 1 occurs in the brightness between the upper screen and the lower screen.

In FIG. 8, when a liquid crystal panel whose transmittance increases in proportion to the signal line driving voltage is used, R
_{Since uh} > R _lh and R _ul > R _ll , VH (upper) −V
Since H (lower) <0 and VL (upper) −VL (lower) <0, the upper screen is darker than the lower screen. Hereinafter, such a difference in brightness between the upper screen and the lower screen is referred to as a vertical luminance difference. The difference between the upper and lower luminances increases as the size of the liquid crystal display device increases, and significantly degrades the display quality of the liquid crystal display device.

[0011]

SUMMARY OF THE INVENTION As described above,
In the wiring method of the driving power supply line of the conventional liquid crystal display device, a wiring resistance difference occurs between the upper and lower signal line driving circuits 15 and the liquid crystal driving power supply circuit 17, and this wiring resistance difference is proportional to the size of the screen of the liquid crystal display device. However, there is a problem in that a luminance difference occurs between the upper and lower portions of the display screen due to a voltage drop due to a wiring resistance difference and a drive power supply line current, and therefore, display quality is significantly reduced.

The present invention solves the above-mentioned conventional problems, and comprises an upper signal line drive power supply line for driving the upper side of a liquid crystal panel driven vertically and a lower signal line for driving the lower side. Each voltage drop can be made substantially the same between the line drive power supply line and the line drive power supply line, and even when displaying an image on a large-screen liquid crystal panel, display unevenness caused by a difference in brightness between the upper and lower lines is eliminated. A method of wiring a driving power supply line of a liquid crystal display device, which is capable of significantly improving image quality by a low-cost and simple method.

[0013]

In order to solve the above-mentioned problems, a method of wiring a drive power supply line of a liquid crystal display device according to the present invention is directed to a liquid crystal display device in which a liquid crystal panel is driven vertically. An upper signal line driving power supply line for driving the upper side and a lower signal line driving power supply line for driving the lower side of the liquid crystal panel. The invention is characterized in that the wiring resistance values are made substantially the same to eliminate the wiring resistance difference.

As described above, between the upper signal line driving power supply line for driving the upper side of the liquid crystal panel driven vertically and the lower signal line driving power supply line for driving the lower side, The voltage drop can be made almost the same, and even when displaying images on a large-screen LCD panel, there is no display unevenness due to the difference in brightness between the upper and lower parts, and the image quality is greatly reduced by a low-cost and simple method. Can be improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to a first aspect of the present invention, there is provided a method of arranging a driving power supply line for a liquid crystal display device, wherein a plurality of signal lines and a plurality of scanning lines are arranged in a matrix, and each intersection is provided at each intersection. A liquid crystal panel that forms a pixel by providing a liquid crystal layer between the disposed electrodes, and drives the liquid crystal layer by switching an applied voltage between the electrodes through the signal line and the scanning line to display an image; A signal line drive circuit that drives the plurality of signal lines for switching, and a scan line drive circuit that drives the plurality of scan lines for the switching,
A liquid crystal driving power supply circuit for supplying the driving voltage for the switching to the signal line driving circuit and the scanning line driving circuit; dividing the plurality of signal lines into upper and lower portions on a liquid crystal panel; In a liquid crystal display device that drives lines by the drive voltage individually supplied through the corresponding signal line drive circuits, a drive power supply line that transmits the drive voltage to upper and lower signal line drive circuits is connected to a branch point. An upper drive power supply line wired from the branch point to the upper terminal point and supplying the drive voltage to the upper signal line drive circuit, and an upper drive power line wired from the branch point to the lower terminal point and driven by the lower signal line drive circuit The upper and lower drive power supply lines are branched from a lower drive power supply line for supplying a voltage, and the upper and lower drive power supply lines have substantially the same electrical characteristics from the branch point to the respective termination points with respect to the branch point. When And how to wire to so that.
According to a fourth aspect of the present invention, there is provided a method of wiring a driving power supply line for a liquid crystal display device, comprising the steps of:
The respective wiring resistances from the drive power supply line to the terminal point on the drive voltage supply side to the upper signal line and from the drive power supply line to the terminal point on the drive voltage supply side to the lower signal line; The wiring is symmetrical between the upper and lower sides with respect to the branch point so that the difference between the respective voltage drops due to the current flowing through the branch point is 8 mV or less.

According to this method, between the upper and lower signal line driving power supply lines, the respective wiring resistance values from the start end to the end thereof are made substantially the same with reference to these branch points. The wiring method of the drive power supply line of the liquid crystal display device according to claim 2,
A plurality of signal lines and a plurality of scanning lines are arranged in a matrix, a liquid crystal layer is provided between electrodes arranged at intersections thereof to form a pixel, and a pixel is formed between the signal lines and the scanning lines. A liquid crystal panel that drives the liquid crystal layer to display an image by switching the applied voltage, a signal line driving circuit that drives the plurality of signal lines for the switching, and the plurality of scanning lines for the switching And a liquid crystal driving power supply circuit for supplying the driving voltage for the switching to the signal line driving circuit and the scanning line driving circuit, and driving the plurality of signal lines up and down on a liquid crystal panel. In a liquid crystal display device in which each of the upper and lower signal lines is driven by the driving voltage individually supplied through the corresponding signal line driving circuit, the upper and lower signal lines A drive power supply line for transmitting the drive voltage to a driving circuit, a branch point, an upper drive power supply line wired from the branch point to an upper terminal point to supply the drive voltage to an upper signal line drive circuit; And a lower driving power supply line that supplies the driving voltage to the lower signal line driving circuit and is wired from the lower end point to the lower driving power supply line. The upper and lower drive power supply lines are wired so that the electrical characteristics of the upper and lower drive power lines are substantially the same with respect to a point, and each of the upper and lower terminal points based on the branch point is grounded by a capacitor, and the respective terminal points are short-circuited. Method.

According to this method, the terminals of the upper and lower signal line driving power supply lines are set to the same potential by the short-circuit line and the capacitor. According to a third aspect of the present invention, there is provided a method of wiring a drive power supply line for a liquid crystal display device, wherein the capacitor for grounding each terminal point according to the second aspect has a capacitance of 10 times or more between all signal lines and all scanning lines. It is a method of connecting a capacitor that has.

According to this method, the impedance of each of the upper and lower signal line driving power supply lines is reduced. Claim 5
The wiring method of the driving power supply line of the liquid crystal display device according to claim 1 includes the step of connecting the driving power supply line according to claim 1 from a branch point thereof to a terminal point on a driving voltage supply side to an upper signal line of the driving power supply line. The difference between the respective voltage drops due to the respective wiring resistances to the drive voltage supply side termination point to the lower signal line of the drive power supply line and the current flowing through the respective drive power supply lines is 8 mV or less. A branch point is moved, and wiring is performed asymmetrically between the upper and lower parts based on the moved branch point.

According to this method, the difference in voltage drop due to the wiring resistance difference between the upper and lower signal line driving power supply lines is reduced by 8 m.
V or less so that the difference in luminance between the upper and lower portions of the liquid crystal panel caused by the difference in wiring resistance can be ignored.

According to a sixth aspect of the present invention, there is provided a wiring method of a drive power supply line of a liquid crystal display device, wherein a drive voltage supply side from a branch point of the drive power supply line to an upper signal line of the drive power supply line is provided. The difference between each wiring resistance between the terminal point and the terminal point on the drive voltage supply side to the lower signal line of the drive power supply line and the voltage drop due to the current flowing through each drive power supply line is 8 mV or less. As described above, between the branch point of the drive power supply line and the start point of either the drive voltage supply side to the upper signal line of the drive power supply line or the drive voltage supply side to the lower signal line of the drive power supply line To insert a resistor into

According to this method, the wiring resistance difference between the upper and lower signal line driving power supply lines is minimized by the insertion resistance, and the luminance difference between the upper and lower portions of the liquid crystal panel caused by the wiring resistance difference can be ignored. To

According to a seventh aspect of the present invention, there is provided a wiring method of a drive power supply line for a liquid crystal display device, wherein a drive voltage supply side from a branch point of the drive power supply line to an upper signal line of the drive power supply line is provided. The difference between each wiring resistance between the terminal point and the terminal point on the drive voltage supply side to the lower signal line of the drive power supply line and the voltage drop due to the current flowing through each drive power supply line is 8 mV or less. Between the branch point of the drive power supply line and the first
A second resistor is inserted between the first resistor and a start point of a drive voltage supply side to a lower signal line of the drive power supply, and the values of the first resistor and the second resistor are adjusted. And

According to this method, the wiring resistance difference between the upper and lower signal line driving power supply lines is adjusted and minimized by the inserted first and second resistors, and the wiring resistance difference is determined by the wiring resistance difference. The resulting difference in brightness between the upper and lower portions of the liquid crystal panel is set to a negligible level.

In each of the above methods, in a liquid crystal display device in which the liquid crystal panel is driven vertically, the upper signal line driving power supply line for driving the upper side of the liquid crystal panel and the lower signal line driving power supply line for driving the lower side of the liquid crystal panel. With respect to the lower signal line driving power supply line, the respective wiring resistance values from the start end to the end thereof are made substantially the same on the basis of their branch points to eliminate the wiring resistance difference.

Hereinafter, a liquid crystal display device employing a driving power supply line wiring method according to an embodiment of the present invention will be specifically described with reference to the drawings. Note that components that operate in the same manner as those of the conventional example shown in FIG. In addition, here, description will be given mainly by taking an STN-type liquid crystal display device, which is a simple matrix type liquid crystal display device, as an example. (Embodiment 1) FIG. 1 is a configuration diagram of a liquid crystal display device employing a wiring method of a drive power supply line according to Embodiment 1 of the present invention. This liquid crystal display device has a liquid crystal panel 14 as shown in FIG.
The signal lines 11 and the scanning lines 12, which are divided into two from the center of the display area, are arranged in a matrix, and the pixel electrodes 13 are formed and arranged at the intersections. The liquid crystal panel 14 is driven by a signal line driving circuit 15 and a scanning line driving circuit 16. A plurality of signal line driving circuits 15 and scanning line driving circuits 16 are arranged around the liquid crystal panel 14 according to the number of signal lines and the number of scanning lines. In the liquid crystal panel 14 of FIG. 1, the number of signal lines 11 is M and the number of scanning lines 12 is 2N. The signal line driving circuit 15 is arranged above and below the liquid crystal panel 14 to perform upper and lower two-division driving for driving the signal line 11 by dividing it vertically.

The upper and lower signal line driving circuits 15 are referred to as an upper signal line driving circuit and a lower signal line driving circuit. The drive power supply voltage of the signal line drive circuit 15 is VH and VL, and is supplied from the liquid crystal drive power supply circuit 17 through a drive power supply line (not shown) for the signal line 11. The drive power supply line for this signal line 11 is composed of a VH drive power supply line 24 and a VL drive power supply line 23 corresponding to the drive power supply voltages VH and VL, and a lower VH drive power supply corresponding to the upper and lower signal line drive circuits 15. Line 19, lower VL
It branches into a drive power supply line 20, an upper VH drive power supply line 21, and an upper VL drive power supply line 22. The driving power supply voltage of the scanning line driving circuit 16 is supplied to the liquid crystal driving power supply circuit 17 through the scanning line driving line 18.
Supplied from

In FIG. 1, upper and lower VH drive power supply lines 2
1 and 19 and the VL drive power supply lines 22 and 20 are shown as vertically symmetrical points, but the upper VH drive power supply line 21
And the lower VH drive power supply line 19 are symmetrically arranged vertically with respect to the branch point of the VH drive power supply line 24. Accordingly, the wiring resistance from the branch point of the upper and lower VH drive power supply lines 21 and 19 to each terminal point has the same value, and since they are symmetrically wired, the impedances are also the same. Similarly, the upper VL drive power supply line 22 and the lower VL drive power supply line 20 are symmetrically wired up and down from a branch point which is a vertical symmetry point. Therefore, the wiring resistances of the upper and lower VL drive power supply lines 22 and 20 are the same, and the impedances are also the same. Furthermore, since the wiring resistance of the VH driving power supply line 24 and the VL driving power supply line 23, which are wirings from the liquid crystal driving power supply circuit 17 to each branch point, is common to the upper and lower signal line driving circuits 15, any wiring may be used. It does not affect the upper and lower wiring resistance difference.

As described above, according to the present invention in which the driving power supply lines for the signal lines 11 are wired symmetrically with respect to the branch point, the signal line driving power supply line current and the wiring resistance of each of the upper and lower driving power supply lines are determined. The voltage drop is the same, and there is no difference in brightness above and below the screen of the liquid crystal panel 14. Further, in a display in which such a vertical luminance difference is a problem, the upper VH drive power supply line 21
And the lower VH drive power supply line 19 have the same value. Similarly, the drive power supply line currents of the upper VL drive power supply line 21 and the lower VL drive power supply line 19 have the same value.

When the upper screen and the lower screen of the upper and lower two-part drive display completely different displays, the drive power supply line currents are different between the upper and lower parts. In such a case, the difference in luminance between the upper and lower parts is not visually recognized. Such indications are extremely rare. On the other hand, there are extremely many cases where the upper screen and the lower screen of the upper and lower two-part drive are similar to each other, and in this case, the upper and lower drive power supply line currents can be regarded as having the same value.

Further, according to the present invention, in which the branch point is symmetrically wired as an upper and lower symmetrical point of the upper and lower drive power supply lines, the wiring resistance and impedance of the upper and lower drive power supply lines can be made completely the same, and a vertical luminance difference occurs. Absent. Further, when the liquid crystal drive power supply circuit 17, the signal line drive circuit 15, and the scanning line drive circuit 16 are mounted on a printed circuit board or a flexible film substrate and wired, the upper and lower drive power supply lines are completely symmetrical with the branch point being symmetrical. It can be formed in a pattern, and the wiring resistance of the upper and lower drive power supply lines can be made simple and accurate.

According to the present invention, the driving power supply line, which is a wiring from the liquid crystal driving power supply circuit 17 to each branch point, is connected to the wiring from the liquid crystal driving power supply circuit 17 to the upper signal line driving circuit 15 and the liquid crystal driving power supply circuit. Signal line drive circuit 1 below 17
Since the wirings are shared by up to five wirings and the arrangement of the drive power supply circuit does not affect the difference between the upper and lower wiring resistances, the degree of freedom in designing the liquid crystal display device is increased. As described above, it is possible to realize the wiring of the driving power supply line which does not cause a vertical luminance difference with a very low cost and simple configuration. (Embodiment 2) FIG. 2 is a configuration diagram of a liquid crystal display device employing a wiring method of a drive power supply line according to Embodiment 2 of the present invention. FIG.
1 is different from the liquid crystal display device shown in FIG. 1 in that a capacitor C is inserted between each terminal point of the upper and lower VH drive power supply lines 21 and 19 and ground, and the upper and lower VH drive power supply lines 21 and 19 are further connected. 19 are short-circuited by VH termination point short-circuit lines 26. Similarly, capacitors C are inserted between the respective termination points of the upper and lower VL drive power supply lines 22 and 20 and ground, and the upper and lower V
Each of the terminal points of the L drive power supply lines 22 and 20 is short-circuited by a VL terminal point short-circuit line 25. The VH terminal point short-circuit line 26 and the VL terminal point short-circuit line 25 are wired symmetrically in the vertical direction when viewed from the vertical symmetry point which is a branch point of the VH drive power supply line 24 and the VL drive power supply line 23.

As described above, according to the driving power supply line wiring method of the second embodiment, the upper and lower driving power supply lines 21, 22, 1
Since the terminal points 9 and 20 are bypassed and short-circuited by the capacitor C, the voltages at the upper and lower terminal points become the same, so that there is no difference between the upper and lower luminance in the liquid crystal panel 14, and
In addition, the wiring impedance of the upper and lower drive power supply lines 21, 22, 19, and 20 can be reduced.

The driving power supply line current in this case is generated by charging and discharging a driving voltage to all the capacitances between the signal lines 11 and the scanning lines 12 of the liquid crystal panel 14. As the impedance of the drive power supply line is lower, the upper and lower drive power supply lines 21, 22, 1
The ripple voltage at each of the termination points 9 and 20 is reduced. Therefore, a capacitor having a capacity of at least 10 times the capacitance between all the signal lines 11 and all the scanning lines 12 is connected to the upper and lower drive power supply lines 21, 22, 19,
20 can be inserted between each termination point and the ground.
As a result, the impedance of the power supply becomes sufficiently small, and the ripple voltage at each terminal point of the upper and lower drive power supply lines 21, 22, 19, and 20 decreases to a level at which there is no practical problem. (Embodiment 3) FIG. 3 is a configuration diagram of a liquid crystal display device adopting the driving power supply line wiring method of Embodiment 3 of the present invention. This liquid crystal display device has a VH drive power supply line 2 as shown in FIG.
The branch point No. 4 is shifted from the vertical symmetry point of the upper and lower VH drive power supply lines 21 and 19 by the length of δL toward the lower VH drive power supply line 19. In this case, although the wiring resistance of the upper and lower VL drive power supply lines 22 and 20 is the same,
Since the wiring resistances of the drive power supply lines 21 and 19 are not symmetrical, a difference occurs between the wiring resistances.

For example, the upper and lower VH drive power supply lines 21 and 19
When the resistance corresponding to the length δL is δRH and the upper and lower VH drive power supply line currents are iH, the respective ends of the VH of the upper signal line drive circuit 15 and the VH of the lower signal line drive circuit 15 A voltage difference of (iH * δRH) occurs between the points. A luminance difference corresponding to this voltage difference is generated on the display screen of the liquid crystal panel 14, and this is a vertical luminance difference on the display screen.

However, in a liquid crystal display device,
If the difference between the signal line driving voltages is within 8 mV, the difference cannot be detected and recognized by human eyes. That is, as long as the difference between the liquid crystal driving voltages of the upper screen and the lower screen of the upper and lower two-part drive is 8 mV or less, there is no practical problem. Therefore, if (iH * δRH) is 8 mV or less, no practical problem occurs.

According to the wiring method of the drive power supply line of the third embodiment, the voltage between the upper and lower VH drive power supply lines 21 and 19 and the V
If the difference between the wiring resistances between the L drive power supply lines 22 and 20 and the liquid crystal drive voltage difference due to the respective drive power supply line currents is 8 mV or less, that is, if the wiring is within the wiring resistance difference of δRH ≦ 0.008 / iH. In this case, there is no difference between the upper and lower luminance on the display screen. For example, in a liquid crystal display device having a screen with a diagonal length of 17 inches, the current i is about 30 mA at the maximum. At this time, δRH
Is about 0.27Ω.

Here, the upper and lower VH drive power supply lines 21 and 19
, The respective wiring resistance differences δRH, δRH, the respective currents of the upper and lower VL drive power supply lines 22 and 20 as iL, the respective wiring resistance differences as δRL, and the respective wiring resistance differences δRH, δRL.
Is based on the respective wiring resistance values of the lower VH drive power supply line 19 and the lower VL drive power supply line 20, and is positive when large and negative when small. In this case, a voltage difference of iH * δRH is generated for the upper and lower VH drive power supply lines 21 and 19, and iL * for the upper and lower VL drive power supply lines 22 and 20.
A voltage difference of δRL occurs. Therefore, the difference in the liquid crystal drive voltage between the upper and lower parts of the screen is (iH * δRH + iL * δRL).

From the above, (iH * δRH + iL * δR
L) If the wiring satisfies ≦ 8 mV, no vertical luminance difference occurs. As described above, since iH and iL are about 30 mA at the maximum in the 17-inch liquid crystal display device, δRH + δRL ≦
What is necessary is to wire so as to satisfy 0.27Ω.
By arranging in this manner, the drive power supply line can be extremely appropriately arranged with respect to the reduction of the luminance difference between the upper and lower portions of the display screen. (Embodiment 4) FIG. 4 is a configuration diagram of a liquid crystal display device employing a wiring method of a drive power supply line according to Embodiment 4 of the present invention. In this liquid crystal display device, as shown in FIG. 4, a resistor R1 as a first resistor is inserted between the starting point of the lower VH drive power supply line 19 and the branch point of the VH drive power supply line 24, and the lower VL drive By inserting a resistor R2 as a second resistor between the starting point of the power supply line 20 and the branch point of the VL drive power supply line 23, the wiring resistance difference is reduced to zero.

That is, (iH * δRH) + (iL * δ
(RL) ≦ 8 mV, when the value of the resistor R1 is R1 and the value of the resistor R2 is R2, (δR
(H-R1) iH + (δRL-R2) iL ≦ 8 mV.

The wiring method of the driving power supply line in the liquid crystal display device shown in FIG. 4 is one embodiment thereof, and the wiring method of the driving power supply line shown in FIGS. 5 and 6 in which the insertion positions of the resistors R1 and R2 are changed. Has the same effect. However,
In the case of FIG. 5, (δRH + R1) iH + (δRL + R
2) Insert R1 and R2 satisfying iL ≦ 8 mV, and in the case of FIG. 6, (δRH + R1) iH + δRL * iL ≦ 8
Insert R1 that satisfies mV. (Embodiment 5) FIG. 7 is a configuration diagram of a liquid crystal display device employing the driving power supply line wiring method of Embodiment 5 of the present invention. As shown in FIG. 7, the liquid crystal display device includes a resistor R1, a resistor R2, a resistor R3, a resistor R3 between each terminal point of the upper and lower drive power supply lines 21, 19, 22, 20 and a corresponding branch point. By inserting R4, the liquid crystal driving voltage difference between VH and VL due to the wiring resistance difference between the upper and lower portions of the screen is reduced to 8 mV or less. That is, (δRH−R1 + R2) i
Each value of the resistor R1, the resistor R2, the resistor R3, and the resistor R4 is set so as to satisfy H + (δRL−R3 + R4) iL ≦ 8 mV.

According to the wiring method of the drive power supply line of each of the above-described embodiments, the upper signal line drive power supply line for driving the upper side of the liquid crystal panel driven vertically and the lower signal line for driving the lower side. Each voltage drop can be made substantially the same between the line drive power supply line and the line drive power supply line, and even when displaying an image on a large-screen liquid crystal panel, display unevenness caused by a difference in brightness between the upper and lower lines is eliminated. The image quality can be greatly improved by a low-cost and simple method.

The wiring method of the drive power supply line in each of the above embodiments can be applied not only to the STN type liquid crystal display device but also to the TFT type liquid crystal display device switching by a thin film transistor.

[0043]

As described above, claims 1 and 4 are as described above.
According to the invention, between the upper and lower signal line driving power supply lines, the respective wiring resistance values from the start end to the end can be made substantially the same with reference to these branch points.

According to the second aspect of the present invention, the terminals of the upper and lower signal line driving power supply lines can be set to the same potential by the short-circuit line and the capacitor. Claim 3
According to the invention, the impedance of each of the upper and lower signal line driving power supply lines can be reduced.

According to the fifth aspect of the present invention, the difference in voltage drop due to the wiring resistance difference between the upper and lower signal line driving power supply lines is set to 8 mV or less, and the upper and lower portions of the liquid crystal panel generated by the wiring resistance difference are reduced. Can be made negligible.

According to the invention of claim 6, the wiring resistance difference between the upper and lower signal line driving power supply lines is minimized by the insertion resistance, and the upper and lower portions of the liquid crystal panel generated by the wiring resistance difference are generated. The luminance difference can be made negligible.

According to the seventh aspect of the invention, the wiring resistance difference between the upper and lower signal line driving power supply lines is adjusted to a minimum by adjusting the inserted first and second resistors. In addition, the difference in brightness between the upper and lower portions of the liquid crystal panel caused by the difference in wiring resistance can be set to a negligible level.

As described above, in the liquid crystal display device in which the liquid crystal panel is driven vertically, the upper signal line driving power supply line for driving the upper side of the liquid crystal panel and the lower signal line for driving the lower side of the liquid crystal panel. With respect to the line drive power supply line, the respective wiring resistance values from the start end to the end of the line drive power supply line can be made substantially the same on the basis of these branch points to eliminate the wiring resistance difference.

Therefore, each voltage between the upper signal line driving power supply line for driving the upper side of the liquid crystal panel driven vertically and the lower signal line driving power supply line for driving the lower side is set. The descent can be made almost the same, and even when displaying images on a large-screen liquid crystal panel, there is no display unevenness caused by the difference in brightness between the top and bottom, and the image quality is greatly reduced by a low-cost and simple method. This effect can be improved, and this effect becomes more conspicuous as the size of the liquid crystal display device increases.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a liquid crystal display device using a driving power supply line wiring method according to a first embodiment of the present invention;

FIG. 2 is a configuration diagram of a liquid crystal display device according to a driving power supply line wiring method according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a liquid crystal display device using a driving power supply line wiring method according to a third embodiment of the present invention;

FIG. 4 is a configuration diagram of a liquid crystal display device using a driving power supply line wiring method according to a fourth embodiment of the present invention.

FIG. 5 is a detailed explanatory diagram of a wiring method according to the fourth embodiment;

FIG. 6 is a detailed explanatory diagram of another wiring method according to the fourth embodiment.

FIG. 7 is a configuration diagram of a liquid crystal display device using a driving power supply line wiring method according to a fifth embodiment of the present invention.

FIG. 8 is a configuration diagram of a liquid crystal display device employing a conventional driving power line wiring method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Signal line 12 Scan line 13 Pixel electrode 14 Liquid crystal panel 15 Signal line drive circuit 16 Scan line drive circuit 17 Liquid crystal drive power supply circuit 18 Scan line drive power supply line 19 Lower VH drive power supply line 20 Lower VL drive power supply line 21 Upper VH drive power supply Line 22 Upper VL drive power supply line 23 VL drive power supply line 24 VH drive power supply line 25 VL terminal point short circuit line 26 VH terminal point short circuit line C Capacitors R1, R2, R3, R4 Resistance

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-280823 (JP, A) JP-A-8-22028 (JP, A) JP-A-61-114226 (JP, A) 67150 (JP, A) JP-A-4-271322 (JP, A) JP-A-3-135597 (JP, A) JP-A-6-202138 (JP, A) JP-A-5-181153 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 1/133 545 G02F 1/1343

Claims (7)

(57) [Claims] 1. A plurality of signal lines and a plurality of scanning lines are arranged in a matrix, and a liquid crystal layer is provided between electrodes arranged at intersections thereof to form pixels, and the signal lines and the scanning lines are formed. A liquid crystal panel that drives the liquid crystal layer to display an image by switching an applied voltage between the electrodes through a signal line; a signal line driving circuit that drives the plurality of signal lines for the switching; and A scanning line driving circuit that drives the plurality of scanning lines; and a liquid crystal driving power supply circuit that supplies a driving voltage for the switching to the signal line driving circuit and the scanning line driving circuit. In a liquid crystal display device, which is divided into upper and lower portions on a liquid crystal panel and each of the upper and lower signal lines is driven by the driving voltage individually supplied through the corresponding signal line driving circuit, The drive power is supplied to the upper and lower signal line drive circuits.
The drive power line that transmits the pressure
From the terminal to the upper termination point, and
An upper drive power supply line for supplying a dynamic voltage;
The drive voltage is routed to the lower signal line drive circuit
And a lower drive power supply line to be supplied.
A line is drawn from the branch point to each end point at the branch point.
The electrical characteristics of the upper and lower drive power supply lines are
Wiring method of the drive power supply line of the liquid crystal display device to be wired in such a manner. 2. The method according to claim 1, wherein a plurality of signal lines and a plurality of scanning lines are connected to a matrix.
Between the electrodes arranged at the intersections
A pixel is formed by providing a liquid crystal layer, and the signal line and the scanning line are formed.
By switching the applied voltage between the electrodes through
A liquid crystal panel for driving the liquid crystal layer to display an image,
A signal for driving the plurality of signal lines for switching
A line drive circuit and the plurality of scans for the switching.
A scanning line driving circuit for driving a scanning line, and the signal line driving circuit
And a scanning line driving circuit.
And a liquid crystal driving power supply circuit for supplying a voltage.
Line is divided into upper and lower lines on the LCD panel,
Signal lines through the corresponding signal line driving circuits.
And the liquid crystal driven by the driving voltage individually supplied
In the display device, the driving power is supplied to upper and lower signal line driving circuits.
The drive power line that transmits the pressure
From the terminal to the upper termination point, and
An upper drive power supply line for supplying a dynamic voltage;
It is wiring to the end point of the driving voltage under the signal line driver circuit
And a lower drive power supply line to be supplied.
A line is drawn from the branch point to each end point at the branch point.
The electrical characteristics of the upper and lower drive power supply lines are
So that the branch point is the base point.
Ground each lower end point with a capacitor, and
A method of wiring a drive power supply line of a liquid crystal display device, characterized by short-circuiting the drive power supply line. 3. A capacitor for grounding each termination point,
3. The method according to claim 2, wherein a capacitor having a capacitance of 10 times or more between all signal lines and all scanning lines is connected. 4. A drive power supply line extending from a branch point thereof to a terminal point on a drive voltage supply side to an upper signal line of the drive power supply line and a drive voltage supply side to a lower signal line of the drive power supply line. The wiring is symmetrically arranged between the upper and lower sides with respect to the branch point so that the difference between the respective voltage drops due to the respective wiring resistances up to the termination point of the wiring and the current flowing through the respective drive power supply lines is 8 mV or less. 4. The method for wiring a drive power supply line of a liquid crystal display device according to item 1. 5. A driving power supply line, from the branch point of that, and to the end point of the driving voltage supply side to the upper signal line of the drive power supply line, the drive voltage supply to the lower signal line of the drive power supply line The branch point is moved such that the difference between each voltage drop due to each wiring resistance to the terminal point on the side and the current flowing through each drive power supply line is 8 mV or less, and the moved branch point is used as a reference.
2. The method according to claim 1 , wherein wiring is performed asymmetrically between upper and lower sides . 6. A drive voltage supply side termination to a drive voltage supply side to a drive voltage supply side to a drive signal supply line to an upper signal line of the drive power supply line from a branch point of the drive power supply line. Between the branch point of the drive power supply line and the upper signal line of the drive power supply line so that the difference between the respective voltage drops due to the respective wiring resistances up to the point and the current flowing through the respective drive power supply lines is 8 mV or less .
The drive voltage supply side or the lower signal line of the drive power supply line
Between the start point of the drive voltage supply side and
2. The wiring method for a drive power supply line of a liquid crystal display device according to claim 1, wherein the drive power supply line is inserted . 7. The driving power supply from a branch point of the driving power supply line
To the end point of the drive voltage supply side to the upper signal line
Termination point of the drive voltage supply side to the lower signal line of the drive power supply line
And the current flowing through each drive power supply line
As a difference under each voltage drop is less 8mV by the prior
A first resistor connected between the driving power supply line and the branch point;
Between the start point of the drive voltage supply side to the lower signal line of the power supply
A second resistor is inserted into each of the first resistor and the second resistor.
2. The liquid crystal display device according to claim 1, wherein the value of the resistor is adjusted.
Wiring method of the drive power supply line.