JP2000003158A - Liquid crystal display - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In a simple matrix liquid crystal panel, a liquid crystal driving voltage decreases as the distance from a power supply end of a scanning electrode decreases, and a luminance gradient occurs. This luminance gradient is corrected by the driving voltage of the signal driver to eliminate luminance unevenness. An upper signal driver, a lower signal driver, and a scanning driver are connected to a simple matrix liquid crystal panel having a plurality of scanning electrodes and a plurality of signal electrodes. The liquid crystal drive voltage generated by the power supply circuit 19 is supplied from the right signal drivers 12q and 15q, and the left signal driver 1 sequentially cascade-connected.
2 and 15. The distribution of the drive voltage is generated by the distributed resistance of the signal voltage connection lines 21 and 22. In this case, the effective driving voltage applied to the liquid crystal cell at an arbitrary position can be offset by the decrease in the scan electrode and the increase in the signal electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device having a simple matrix liquid crystal panel, and more particularly to a liquid crystal display device having a small luminance gradient in a large and high definition liquid crystal panel.

[0002]

2. Description of the Related Art In recent years, the display capacity of a liquid crystal display device has been dramatically increased, and the liquid crystal display device has been widely used as a display for a personal computer, a monitor, or the like due to its thinness and lightness. Among them, the simple matrix type liquid crystal display device has a feature that it is relatively inexpensive and good display characteristics can be obtained.

FIG. 5 is a circuit diagram of a conventional liquid crystal display device. The liquid crystal display device shown in the figure includes a simple matrix liquid crystal panel 10, upper signal drivers 12a, 12b,.
.. 12q and lower signal drivers 15a, 15b ...
15q and scanning drivers 17a, 17b... 17n
have. The upper signal driver 12 is the circuit board 11
, And the lower signal driver 15 is mounted on the circuit board 14. The signal drivers 12a, 12b,... Are cascaded through the signal lines 13 and drive the signal electrodes on the upper side of the simple matrix liquid crystal panel 10.
It is. The signal drivers 15a, 15b,... Are cascaded through similar signal lines 16 to drive the signal electrodes on the lower side of the simple matrix liquid crystal panel 10.
C.

Scan drivers 17a, 17b... 17n
Are ICs for driving the scanning electrodes of the simple matrix liquid crystal panel 10, each of which is cascaded and connected to the circuit board 2.
0 is implemented. The controller 18 is a controller that outputs control signals and data to the signal drivers 12 and 15 and the scanning driver 17. The power supply circuit 19
Via the signal drivers 12 and 15 and the scanning driver 17,
A power supply for supplying a liquid crystal driving voltage to the simple matrix liquid crystal panel 10.

The liquid crystal driving voltages supplied to the simple matrix liquid crystal panel 10 from the signal drivers 12, 15 and the scanning driver 17 are generated in a combination as shown in FIG. That is, according to the non-inversion / inversion (H / L), selection, non-selection, and non-display states of the AC signal, any one of the liquid crystal driving voltages V _H , V _L , and V _M is output from the signal driver. It is supplied, also V _{R +} from the scan driver, V _R-, either the liquid crystal driving voltage V _M is supplied. Here, the AC signal is a control signal for instructing whether to perform non-inverting drive or inverting drive because the characteristics of the liquid crystal deteriorate unless the liquid crystal panel is AC-driven.

[0006]

However, the signal electrodes and the scanning electrodes of the simple matrix liquid crystal panel 10 are I
Since it is composed of a transparent electrode such as TO, it has a resistance value. In a large-sized liquid crystal panel of 12 inches or more, an ITO electrode having a sheet resistance of about 3 to 7 ohms is generally used. As a result, the liquid crystal driving voltages V _{R +} , V _R− supplied from the scanning driver 17 to each liquid crystal cell of the simple matrix liquid crystal panel 10.
However, there is a problem that the voltage decreases as the distance from the scanning-side power supply end increases, and the display of the simple matrix liquid crystal panel 10 becomes brighter at the scanning-side power supply end and darker as the distance from the scanning-side power supply end increases. Such luminance unevenness is called a luminance gradient.

The present invention has been made in view of such a conventional problem, and increases the liquid crystal driving voltage supplied from a signal driver to a simple matrix liquid crystal panel as the distance from the scanning side power supply end increases. It is another object of the present invention to reduce a luminance gradient of a simple matrix liquid crystal panel by compensating for a decrease in a scanning liquid crystal driving voltage supplied from a scanning driver.

[0008]

In order to achieve this object, the invention according to claim 1 of the present application provides a simple structure in which a plurality of scanning electrodes and a plurality of signal electrodes are formed in a matrix with a liquid crystal cell interposed therebetween. A matrix liquid crystal panel, a plurality of scanning drivers for sequentially applying a scanning liquid crystal driving voltage from a power supply end of each of the scanning electrodes, and a plurality of signal drivers for applying a data liquid crystal driving voltage to the signal electrodes according to input data; A liquid crystal controller that supplies a desired control signal to the scan driver and supplies display data to the signal driver; and at least selection and non-selection of a liquid crystal cell for the plurality of scan drivers and the plurality of signal drivers. , And a power supply circuit for supplying a non-display liquid crystal drive voltage,
The power supply circuit sets a plurality of signal electrodes in the simple matrix liquid crystal panel as first, second,... (N−1), and n-th signal electrodes from a power supply end to a terminal of the scanning electrode. At this time, the n-th, (n−1),...,
The liquid crystal driving voltage is applied in the order of the first signal electrodes.

According to a second aspect of the present invention, in the liquid crystal display device according to the first aspect, the signal driver is configured such that m (≦ n) continuous m (≦ n) of the n signal electrodes of the simple matrix liquid crystal panel. M driving elements for driving signal electrodes; and a constant distributed resistance for distributing the liquid crystal driving voltage output from the power supply circuit to the m driving elements in descending order. And a liquid crystal drive voltage line provided with an end and an output end for applying a liquid crystal drive voltage to another signal driver with the distributed resistance interposed therebetween.

According to such a configuration, the liquid crystal driving voltage for data is supplied from the signal driver located farthest from the scanning-side power supply terminal, and the driving voltage of the scanning liquid crystal driving voltage increases as the distance from the power supply end increases. The decrease is compensated for by the data liquid crystal drive voltage.

According to a third aspect of the present invention, there is provided a simple matrix liquid crystal panel in which a plurality of scanning electrodes and a plurality of signal electrodes are formed in a matrix with a liquid crystal cell interposed therebetween, and each of the scanning electrodes is provided with a scanning liquid crystal drive. A scan driver group for sequentially applying a voltage, a signal driver group for applying a data liquid crystal drive voltage to each of the signal electrodes in accordance with input data, and a desired control signal to the scan driver group; A liquid crystal controller that supplies data for display to the plurality of scan driver groups and the plurality of signal driver groups, at least selection of a liquid crystal cell, non-selection, and a power supply circuit that supplies a non-display liquid crystal drive voltage; The simple matrix liquid crystal panel includes a plurality of first and second signal electrodes extending from a power supply end to an end of the scan electrode.
.., (N-1) and n-th signal electrodes, and the first, second,... (N-1) and n-th signal electrodes are respectively provided with resistors R1 and R2. ,... R (n-1), Rn are connected to each other through the respective resistors Ri (i = 1 to n) to the output terminal of the driving voltage of the signal driver group. > R
2>...> R (n-1)> Rn.

According to such a configuration, the resistance value of the signal electrode located farthest from the scanning-side power supply end of the simple matrix panel is reduced, and the resistance value of the signal electrode located closest is increased. Attach In this manner, the decrease in the scanning liquid crystal driving voltage that increases as the distance from the scanning side power supply end increases is compensated for by the data liquid crystal driving voltage.

[0013]

(Embodiment 1) A liquid crystal display device according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a circuit configuration of a liquid crystal display device according to the present embodiment, and the same parts as those in the conventional example are denoted by the same reference numerals. This liquid crystal display device
Simple matrix liquid crystal panel 10, upper signal driver 1
2a, 12b,... 12q and lower signal driver 1
.. 15q, the upper signal driver 12 is mounted on the circuit board 11 and the lower signal driver 15 is mounted on the circuit board 14 as in the conventional example.

The plurality of signal electrodes in the simple matrix liquid crystal panel 10 are the first, second,... (N−1), and n-th signal electrodes from the power supply end to the end of the scanning electrode. First signal driver 12a, second signal driver 1
2b... The nth signal driver 12q is an IC that is cascaded through the cascade connection signal line 13 and drives the upper half signal electrodes of the simple matrix liquid crystal panel 10 according to input data. Further, the first signal driver 15a, the second signal driver 15b,..., The n-th signal driver 15q are cascaded through similar signal lines 16, and the lower half signal electrodes of the simple matrix liquid crystal panel 10 respond to input data. It is an IC that is driven.

Scan drivers 17a, 17b... 17n
Are ICs for sequentially driving the scanning electrodes of the simple matrix liquid crystal panel 10, each of which is cascaded and mounted on the circuit board 20. The controller 18 is a liquid crystal controller that outputs control signals and display data to the signal drivers 12 and 15 and the scanning driver 17. The power supply circuit 19 is a power supply that supplies a liquid crystal driving voltage for at least selection, non-selection, and non-display of a liquid crystal cell to the simple matrix liquid crystal panel 10 via the signal drivers 12 and 15 and the scanning driver 17. As shown in FIG. 6, this liquid crystal driving voltage is V
_R +, V _R-, supplies a liquid crystal drive voltage V _M, and supplies liquid crystal drive voltage of the V _H, V _L, V _M to the signal driver 12 and 15.

The power supply circuit 19 supplies signal drivers 12 and 15
Is different from the conventional example in that the signal drivers 12p,.
The liquid crystal drive voltage is supplied to 2b and 12a, and each signal driver 15p,.
The liquid crystal driving voltage is supplied to 5b and 15a. The n-th signal driver 12q is an upper signal driver located farthest from the scanning-side power supply end, and connects a power supply line connecting each signal driver 12 to the signal voltage connection line 2.
Called 1. Similarly, the n-th signal driver 15q is a lower signal driver located farthest from the scanning-side power supply end, and a power supply line connecting each signal driver 15 is referred to as a signal voltage connection line 22. Thus, the connection direction of the signal lines 13 and 16 and the connection direction of the signal voltage connection lines 21 and 22 are opposite.

FIG. 2 is a connection diagram specifically showing the configuration of the input / output terminals of the signal driver in the broken line portion of FIG. 1. Since each signal driver is the same, the signal driver 15q will be described. The signal driver 15q shown in FIG.
240 the output terminal 31 of the liquid crystal drive the liquid crystal driving voltage V _M, V _H, V _L of the input terminals 32a, 32b, 32c,
Liquid crystal drive voltage V _M, V _H, V _L of the output terminals 33a, 33
b and 33c are provided respectively. The input terminal 32 and the output terminal 33 are passed through three liquid crystal drive voltage lines 34.
And are connected. The signal driver 15q receives a control signal and data from the controller 18 in FIG.
V _H, V _L, by selecting one of the voltage V _M output from the output terminals 31.

FIG. 3 is an equivalent circuit diagram of the liquid crystal drive voltage line 34 of the signal driver 15q. Generally a signal driver 1
In the chip shape of 5q, the length in the long side direction along the liquid crystal drive voltage line 34 is about 20 mm, and the length in the short side direction is about 1/10 of the length in the long side direction. Signal driver 15
Since the IC of q has such an elongated shape, the liquid crystal drive voltage line 34 can be expressed by a resistance distributed constant circuit as shown in FIG.

The liquid crystal drive voltage generated by the power supply circuit 19 of FIG. _{1 V H, V L, V} M is the signal driver 12q farthest from scanned first side feeding end, of each liquid crystal driving voltage of 15q It is input to the input terminal 32. Then, the voltage is output to the output terminal 33 of each liquid crystal driving voltage through the liquid crystal driving voltage line 34 inside the signal driver. During this time, for example, m = 240 drive elements (switching transistors) of the signal driver 15q are turned on or off, and the liquid crystal drive voltage is applied according to the distributed resistance value of the liquid crystal drive voltage line. The voltage applied to the switching transistor at this time decreases as it approaches the input terminal 32 to the output terminal 33 side.

For example, if the number n of signal electrodes on the upper or lower side of the simple matrix liquid crystal panel 10 is 240, the number of signal drivers 15q on the lower side is one. The AC conversion signal is set to H, and the liquid crystal drive voltages generated by the power supply circuit 19 when the pixels are selected are set to V _H and V _R- . The liquid crystal driving voltage of the output terminal 33b side of FIG. 2 and V _H - [Delta] V _H, the right end of the output terminal 3
The liquid crystal driving voltage applied to the scanning electrode of the liquid crystal cell connected to 1 is V _R− −ΔV _R− . In this case, the voltage Vsel is applied from the right end of the simple matrix liquid crystal panel 10 in the i-th liquid crystal _{cell, Vsel = {V H - (} i / 240) ΔV H} - [V R- -
｛(240-i) / 240｝ ΔV _R- ].

Here, if the value of the distributed resistance of the liquid crystal driving voltage line 34 is set so that ΔV _H = | ΔV _R− | = ΔV, Vsel = (V _H −V _R− ) + ｛(− i− 240 + i) / 240｝ ΔV = (V _H −V _R− ) −ΔV, and the voltage applied to the i-th liquid crystal cell is a voltage independent of i. This means that the effective voltages of the 240 liquid crystal cells driven by the same scanning electrode are the same.

As described above, since the liquid crystal driving voltage for data is supplied from the signal drivers 12q and 15q farthest from the scanning-side power supply end, the voltage value there is the largest, and the liquid crystal inside the signal driver is increased. By using the resistance value of the drive voltage line, the voltage value can be reduced as it approaches the scanning-side power supply end. For this reason, not only when ΔV _H = | ΔV _R- |, but also when ΔV _H ≒ | ΔV _R- |, the lowering of the scanning liquid crystal drive voltage as the distance from the scanning side power supply end decreases. And the brightness gradient of the liquid crystal panel can be reduced.

As described above, according to the present embodiment, the luminance gradient, which is a problem particularly in a large liquid crystal panel of 12 inches or more,
It can be eliminated without adding any components. By doing so, the display quality of the liquid crystal display panel can be improved without impairing the practical feature that the simple matrix liquid crystal panel is lower in price than the active matrix liquid crystal panel.

(Embodiment 2) Next, a liquid crystal display device according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 4 is a block diagram showing a circuit configuration of a part of the liquid crystal display device of the present embodiment, and shows a lower half of a simple matrix liquid crystal panel. As in the conventional example, a controller and a power supply circuit are provided (not shown), and a simple matrix liquid crystal panel 40 is connected to a signal driver group 41 and a scan driver group 42. The signal electrodes of the simple matrix liquid crystal panel 40 shown in the figure are n = m × 16 = 240 × 16
= 3840 lines.

The signal driver group 41 is a circuit block in which a plurality of the signal drivers described in the first embodiment are cascaded, and has 3,840 output terminals.
The scan driver group 42 is also a plurality of scan drivers cascade-connected, and has the same number of output terminals as the number of scan electrodes of the simple matrix type liquid crystal panel 40. The simple matrix liquid crystal panel 40 has an extraction electrode 43 and a display electrode 44, and is connected to the signal driver group 41 via the extraction electrode 43.

The extraction electrode 43 is connected from the power supply end side to the end side of the scanning electrode with resistors R1, R2, R3,.
1), Rn (here, n = 3840) is an extraction electrode whose resistance value is formed so as to satisfy the relationship of R1>R2>R3> ... R3839> R3840. In FIG. 4, the scanning electrodes are omitted for easy understanding.

In the liquid crystal display device configured as described above, the liquid crystal driving voltages V _H and V _L supplied to the display electrode 44 located farthest from the scanning driver group 42 become the largest, and the scanning driver group The closer to 42, the lower the liquid crystal drive voltage. As a result, a decrease in the effective voltage due to a decrease in the value of the scanning liquid crystal driving voltage as the distance from the scanning-side power supply end increases can be compensated for by the voltage of the signal electrode, that is, the extraction electrode. Thus, the luminance gradient of the liquid crystal panel can be reduced.

[0028]

As described above, according to the first and second aspects of the present invention, the data liquid crystal drive voltage is supplied from the signal driver located farthest from the scanning side power supply end.
The lowering of the scanning liquid crystal driving voltage as the distance from the scanning side power supply end increases can be compensated for by the data liquid crystal driving voltage. Therefore, the brightness gradient of the liquid crystal panel can be reduced.

According to the third aspect of the present invention, the resistance value of the signal electrode of the simple matrix liquid crystal panel is inclined from the scanning side power supply end, so that the scanning liquid crystal becomes farther from the scanning side power supply end. The decrease in the drive voltage can be compensated for by the data liquid crystal drive voltage. Therefore, the brightness gradient of the liquid crystal panel can be reduced.

As described above, according to the present invention, the luminance gradient, which is a problem particularly in a large liquid crystal panel of 12 inches or more, can be solved without adding any components. The display quality of the liquid crystal panel can be improved without impairing the feature of being lower in price as compared with the panel.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a liquid crystal display device according to Embodiment 1 of the present invention.

FIG. 2 is a connection diagram illustrating input / output terminals of a signal driver used in the liquid crystal display device according to the first embodiment;

FIG. 3 is an equivalent circuit diagram of a liquid crystal drive voltage line in the signal driver according to the first embodiment.

FIG. 4 is a circuit configuration diagram centering on a simple matrix liquid crystal panel in a liquid crystal display device according to a second embodiment of the present invention.

FIG. 5 is a circuit configuration diagram of a conventional liquid crystal display device.

FIG. 6 is an explanatory diagram showing a combination of liquid crystal driving voltages in a simple matrix liquid crystal panel.

[Explanation of symbols]

 10, 40 Simple matrix liquid crystal panel 11, 14, 20 Circuit board 12, 15 Signal driver 13, 16 Signal line 17 Scan driver 21, 22, Signal voltage connection line 18 Controller 19 Power supply circuit 31, 33 Output terminal 32 Input terminal 41 Signal driver Group 42 Scan driver group 43 Leader electrode 44 Display electrode R1, R2, ... R3839, R3840 Resistance

Claims (3)

[Claims] 1. A simple matrix liquid crystal panel in which a plurality of scanning electrodes and a plurality of signal electrodes are formed in a matrix with a liquid crystal cell interposed therebetween, and a scanning liquid crystal driving voltage is sequentially applied from a power supply end of each scanning electrode. A plurality of scan drivers, a plurality of signal drivers that apply a data liquid crystal drive voltage to the signal electrodes according to input data, and a desired control signal to the scan driver.
A liquid crystal controller that supplies display data to the signal driver; and a power supply circuit that supplies at least liquid crystal cell selection, non-selection, and non-display liquid crystal drive voltages to the plurality of scan drivers and the plurality of signal drivers. , The power supply circuit comprises: a plurality of signal electrodes in the simple matrix liquid crystal panel, from a power supply end of the scan electrode to a terminal end, a first, a second,... , The (n-1) -th,..., The second signal electrodes are applied in the order of the n-th, (n−1),. A liquid crystal display device characterized by giving. 2. The signal driver, comprising: m driving elements for driving m (≦ n) consecutive signal electrodes of the n signal electrodes of the simple matrix liquid crystal panel; The liquid crystal driving voltage output from the power supply circuit is distributed to the elements in a descending order, and has a constant distributed resistance. The liquid crystal driving voltage is supplied to another signal driver across the input end of the liquid crystal driving voltage and the distributed resistance. 2. The liquid crystal display device according to claim 1, further comprising: a liquid crystal drive voltage line provided with an output terminal for supplying the voltage. 3. A simple matrix liquid crystal panel in which a plurality of scanning electrodes and a plurality of signal electrodes are formed in a matrix with a liquid crystal cell interposed therebetween, and a group of scanning drivers for sequentially applying a scanning liquid crystal driving voltage to each of the scanning electrodes. A signal driver group that supplies a data liquid crystal drive voltage to each signal electrode according to input data; and a liquid crystal that supplies a desired control signal to the scan driver group and supplies display data to the signal driver group. A controller, and a power supply circuit for supplying at least liquid crystal cell selection, non-selection, and non-display liquid crystal driving voltages to the plurality of scan driver groups and the plurality of signal driver groups, the simple matrix liquid crystal. The panel is configured to connect the plurality of signal electrodes to first, second,..., (N−1), and n-th signal electrodes from the power supply end to the end of the scanning electrode. The first, second,... (N-1),
Resistances R1, R2,... R (n-1), Rn are respectively applied to the n-th signal electrode.
, And connected to the output terminal of the drive voltage of the signal driver group via the respective resistors Ri (i = 1 to n), and sets the values of the respective resistors to R1>R2>...> R (n-1 )> Rn.