JPH1138388A - Driving method of liquid crystal display device and liquid crystal display device - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To provide a driving method of a liquid crystal display device which can make the contrast characteristics of the liquid crystal display device uniform due to a characteristic error or a manufacturing error of a two-terminal type nonlinear resistance element. Main purpose. SOLUTION: A signal line side signal is outputted to a signal line side electrode of a liquid crystal display device, and a reverse selection negative voltage signal 3 is outputted to a scanning line side electrode.
In a driving method of a liquid crystal display device that drives a liquid crystal display device by outputting a scanning line side signal composed of a set of a positive selection positive voltage signal 32 and a negative selection positive voltage signal 32, The contrast characteristic of the liquid crystal display device is corrected by changing the duty ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving a liquid crystal display device for driving a liquid crystal display device in a communication terminal such as a portable telephone, an electronic organizer, and a display device, and a driving device for the liquid crystal display device. The present invention relates to a method for driving a liquid crystal display device capable of correcting contrast characteristics of a liquid crystal display device having a two-terminal nonlinear element, and a liquid crystal display device.

[0002]

2. Description of the Related Art For example, MIM (Metal-Insulator-Meta
l) As a display device using a liquid crystal display device provided with a two-terminal non-linear resistance element such as an element, a display device having a configuration shown in FIG. 6 is conventionally known. The display device 10 shown in FIG.
An X driver 12 for outputting a signal line side signal to a signal line side electrode of a transmission type liquid crystal panel 11, and a scanning line side signal comprising a set of a reverse selection negative voltage signal and a positive selection positive voltage signal to a scanning line side electrode. And Y drivers 13 and 13 for outputting the same.

In this display device 10, when the arrangement of liquid crystal elements in a predetermined portion of the liquid crystal panel 11 is changed to display black, as shown on the left side of FIG. In the first half of one horizontal period (1H), for example, a reverse selection negative voltage signal 21 of -25 V is output to all the scanning line side electrodes in the row direction including the liquid crystal element, and the second half of one horizontal period (1H) In, for example,
A 30V positive selection positive voltage signal 22 is output. At this time, the X driver 12 outputs, for example, a signal line side signal 23 of 0 V at the timing of driving the liquid crystal element, as shown on the left side of FIG. This allows
The scanning line side signal and the signal line side signal are applied to both ends of the MIM element, and the voltage difference between the both ends exceeds the operating voltage of the MIM element. As a result, the liquid crystal element is driven into a non-transmissive state by changing the arrangement. As a result, a black color is displayed.

On the other hand, when displaying in white without changing the arrangement state of the liquid crystal elements, as shown on the right side of FIG. In the first half of 1H), for example, the negative selection negative voltage signal 24 of -30 V is output, and in the second half of one horizontal period (1H), for example, the positive selection positive voltage signal 2 of 25 V
5 is output. At this time, the X driver 12 operates at the timing of driving the liquid crystal element, as shown in FIG.
As shown on the right side of FIG.
Is output. In this case, since the voltage difference between both ends of the MIM element does not exceed the operating voltage, the liquid crystal element maintains a transmissive state without changing the arrangement, and as a result, displays white. As described above, in the display device 10, the Y driver 13, 13 drives the liquid crystal panel 11 by outputting the scanning line side signal having the 50% duty ratio in one horizontal period. Further, the Y driver 13 is driven by the scanning line side signal composed of the reverse selection negative voltage signal and the positive selection positive voltage signal, and compared with the case where the Y driver 13 is driven simply by the scanning line side signal of the positive voltage. It is possible to improve the contrast ratio.

[0005]

However, the conventional display device 10 has the following problems.

That is, the pool of the MIM type liquid crystal panel
As shown in FIG. 4, the I / V characteristic (hereinafter, also simply referred to as “I / V characteristic”) in the Frenkel plot is such that the value of log (I / V) with respect to the drive voltage V of the scanning line signal is normal. For a certain I / V characteristic C1, there are two types of variations of the I / V characteristic C2 and the I / V characteristic C3 shown in FIG. More specifically, the I / V characteristic C2 is expressed as
The slope β of the value of g (I / V) (tan-1 ((m
3-m4) / (10V-4V))) is the I / V characteristic C1
(In the figure, tan-1 ((m1 -m2) / (1
0V-4V))), but the characteristics of the MIM element are shifted in parallel along the drive voltage axis because the ON resistance of the MIM element is higher or lower than that of the MIM element having the I / V characteristic C1. ing. On the other hand, the I / V characteristic C3 has a slope (tan-1 ((m5 -m6) / (10V
-4V)) itself is different from the normal I / V characteristic C1.

Here, when the MIM type liquid crystal panel has the I / V characteristic C2, for example, a volume for varying the driving voltage of the scanning line side signal is provided on the display device 10, and the volume is changed. By adjusting, the contrast can be set to be substantially the same as the normal I / V characteristic C1.

However, an MIM having an I / V characteristic C3
In the type liquid crystal panel, even if the driving voltage of the scanning line side signal is changed, the same contrast as the normal I / V characteristic C1 cannot be set. That is, as shown in FIG. 5, in the contrast characteristic CR1 of the MIM type liquid crystal panel having the I / V characteristic C1, for example, when the scanning line side signal is the voltage V0, the value is (b11 / a11). I
In the contrast characteristic CR3 of the MIM type liquid crystal panel having the / V characteristic C3, when the scanning line side signal is at the voltage V0,
Value (b12 / a12). In this case, even if the drive voltage of the scanning line side signal is changed by the volume,
Since the slope of the contrast characteristic is different, the I / V characteristic C1
Characteristics CR1 of MIM type liquid crystal panel having
Cannot be the same as As a result, the conventional display device 10 has a problem that it is difficult to maintain a constant quality including its contrast characteristics.

For example, when the luminance of the liquid crystal panel 11 is set to a plurality of gradations by pulse width modulation of the signal line side signal, for example, the driving voltage of the scanning line side signal is set to V
When the value is 0, the luminance of the contrast characteristic CR1 is the value (b12), whereas the luminance of the contrast characteristic CR3 is the value (b12). For this reason, there is also a problem that the set luminance gradation differs from the actual luminance gradation. In this case, when a full-color liquid crystal display device is configured with three colors of red, green, and blue (hereinafter, also referred to as “RGB”), since the luminance gradation of each of the three RGB colors is different, the designated color and the actual color are different. There is also a problem that the colors are different.

The present invention has been made to solve such a problem, and can make the contrast characteristics of a liquid crystal display device uniform due to a characteristic error or a manufacturing error of a two-terminal nonlinear resistance element. A main object is to provide a driving method of a liquid crystal display device and a liquid crystal display device.

[0011]

According to a first aspect of the present invention, there is provided a method of driving a liquid crystal display device, comprising the steps of: outputting a signal line signal to a signal line electrode; In a method for driving a liquid crystal display device that outputs a scanning line side signal including a set of a voltage signal and a positive selection positive voltage signal, the duty ratio between the reverse selection negative voltage signal and the positive selection positive voltage signal is varied. The contrast characteristic of the liquid crystal display device is corrected.

In this method of driving a liquid crystal display device, when the I / V characteristic of the liquid crystal display device to be driven is different from that of a normal liquid crystal display device having the I / V characteristic C1, the signal of the scanning line side is inverted. The duty ratio between the selected negative voltage signal and the positive selected positive voltage signal is varied. In this case, if the duty ratio of the positive-selection positive voltage signal changes, the response of a two-terminal non-linear resistance element such as an MIM element to the positive-selection positive voltage signal (hereinafter, a representative example of the MIM element will be described). Characteristics can be changed. That is, by varying the duty ratio of the positive selection positive voltage signal, it is possible to control the slope β in the I / V characteristics of the MIM element. Therefore, it is possible to arbitrarily correct the I / V characteristics that fluctuate due to the characteristic error and the manufacturing error of the MIM element, so that the contrast characteristics of the liquid crystal display device can be made uniform.

According to a second aspect of the present invention, there is provided a method of driving a liquid crystal display according to the first aspect.
It is characterized in that the luminance gradation of the liquid crystal display device is controlled by pulse width modulation of the signal line side signal.

In this method of driving a liquid crystal display device, the luminance gradation of the liquid crystal display device is controlled by pulse width modulation of the signal pulse width of the signal on the signal line side. In this case, M
As a result that the I / V characteristics of the IM element can be made uniform, the set luminance gradation always coincides with the actual luminance gradation. In addition, even when full color is formed using three colors of RGB, the set color always matches the actually displayed color, so that it is possible to achieve uniform display colors.

According to a third aspect of the present invention, there is provided a method of driving a liquid crystal display device according to the first or second aspect, wherein at least one of a minimum value of the negative voltage signal for negative selection and a maximum value of the positive voltage signal for positive selection. It is characterized in that the contrast characteristic of the liquid crystal display device is corrected by correcting one of them.

Although the contrast characteristic can be corrected by changing the duty ratio of the positive selection positive voltage signal in the scanning line signal, the contrast value with respect to the driving voltage of the scanning line signal is automatically made uniform. Not something. In such a case, a display device in which contrast is adjusted by varying the drive voltage of a scanning line side signal using an adjustment volume is used when a liquid crystal display device whose I / V characteristics are originally normal is used. In the case where the same contrast is set, the rotational position of the volume is different from the case where the liquid crystal display device whose characteristics are corrected is used. In this liquid crystal display device driving method, the contrast characteristic with respect to the rotational position of the volume is corrected by correcting at least one of the minimum value of the negative voltage signal for negative selection and the maximum value of the positive voltage signal for positive selection of the scanning line side signal. It can be made uniform.

According to a fourth aspect of the present invention, there is provided a liquid crystal display device.
4. A driving means for generating and outputting the signal line side signal and the scanning line side signal according to the driving method of the liquid crystal display device according to any one of the above items.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a liquid crystal display driving method and a liquid crystal display according to the present invention will be described below with reference to the accompanying drawings. The display device 1 using the liquid crystal display device has a different driving method from the conventional display device 10 shown in FIG. 6, but has the same configuration.
A method of driving the liquid crystal panel 11 by the X driver 12 and the Y driver 13 corresponding to the driving means of the liquid crystal display device according to the present invention will be described in detail with reference to FIG.

The essential feature of the display device 1 according to this embodiment is that, according to the I / V characteristics, as shown in FIG. That is, the duty ratio of the signal 32 is varied.

The method of driving the liquid crystal panel 11 when the slope β of the I / V characteristic of the liquid crystal panel 11 is different from the normal I / V characteristic will be described below with reference to FIGS.
This will be described with reference to FIG.

FIG. 3A shows each MIM of the liquid crystal panel 11.
3. The slope β in the I / V characteristic of the element is, for example, a normal value.
The contrast characteristic CR11 when it is assumed to be 0 is shown. Also, in the figure, the Y axis indicates the transmittance, and X
The axis indicates the scanning line side signal voltage. Further, in the contrast characteristic CR11, the duty ratio of the positive selection positive voltage signal to the signal width of the scanning line side signal output from the Y driver 13 is substantially 50%, that is, the positive selection positive voltage signal 32, shown in FIG. When the pulse width of 32 (hereinafter referred to as “pulse width w”) is set to 30 μS, which is about ＨH, the driving luminance when the signal line side signal of the ON signal and the OFF signal is output from the X driver 12 Characteristic 4
1 and a non-driving luminance characteristic 42 are shown.
In the contrast characteristic CR11, for example, when the driving voltage of the scanning line side signal is the value V1, the contrast value (b
1 / a1) is obtained.

On the other hand, when the value of the slope β in the I / V characteristic of each of the MIM elements of the liquid crystal panel 11 varies in a direction of increasing to, for example, 5.0, the liquid crystal panel 11 has the contrast characteristic shown in FIG. It has CR12.
In this case, the contrast when the driving voltage of the scanning line side signal is the value V1 is the value (b2 / a2), which is different from the contrast characteristic CR11. Further, the contrast characteristic C
R12 has such a characteristic that the change in contrast with respect to the drive voltage of the scanning line side signal also changes sharply. In such a case, even if the drive voltage of the scanning line side signal is changed, the contrast characteristic CR12 cannot be made the same as the contrast characteristic CR11.

In such a case, in the display device 1 according to this embodiment, as shown in FIG. 1, the pulse width w of the positive selection positive voltage signal 32 in the scanning line side signal output from the Y driver 13 is set to, for example, , Set to 10 μS. As a result, the response of the MIM element to the positive selection positive voltage signal 32 in the liquid crystal panel 11 becomes slower, so that the slope β in the I / V characteristic becomes smaller. As a result, the liquid crystal panel 11 becomes as shown in FIG. It has the contrast characteristic CR13. In the contrast characteristic CR13, the contrast when the driving voltage of the scanning line side signal is the value V2 becomes the value (b1 / a1), and the contrast characteristic CR11 in FIG. Become. That is, the liquid crystal panel 11
The liquid crystal device has a characteristic that the followability of the transmittance change of the liquid crystal element to the positive selection positive voltage signal 32 tends to decrease.

Therefore, by disposing a volume for contrast adjustment in the display device 1 and varying the volume to vary the drive voltage of the scanning line side signal, substantially, as shown in FIG. The contrast characteristic can be corrected to the same as the contrast characteristic CR11.

In this case, as shown in FIG. 2, if the drive voltage of the positive selection positive voltage signal 33 is set to a high voltage, the contrast characteristic with respect to the rotational position of the contrast adjustment volume is changed. ) Can be the same as the contrast characteristic CR11 shown in FIG. In other words, if the drive voltage of the scanning line side signal is corrected, FIG.
The contrast characteristic CR13 of FIG. 7 moves in parallel along the drive voltage axis of the scanning line side signal. Therefore, for example, in the display device 1 using the liquid crystal panel 11 having the contrast characteristic CR11, the rotation position of the volume at which the driving voltage of the scanning line signal becomes the value V1, and the scanning is performed in the display device 1 using the liquid crystal panel 11 having the contrast characteristic CR13. If the maximum value of the drive voltage of the positive selection positive voltage signal 33 is corrected so that the rotational position of the volume at which the drive voltage of the line signal becomes the value V1 is the same position, the volume of the volume of the liquid crystal panel 11 of the contrast characteristic CR13 is corrected. The contrast characteristic with respect to the rotational position apparently shifts to a contrast characteristic CR4 shown in FIG. Therefore, the contrast value for the rotational position of the volume can be made uniform.

Further, even when the luminance gradation of the liquid crystal panel 11 is controlled by changing the pulse width of the signal line side signal 26 shown in FIG. As a result of making the characteristics uniform, it is possible to always match the set luminance gradation with the actual luminance gradation. Therefore, even when a full-color two-terminal liquid crystal display device is configured using three color filters of RGB, it is possible to always match the set color with the actually displayed color.

As described above, according to the display device 1 of this embodiment, the contrast caused by the characteristic error of the MIM element itself or the variation of the I / V characteristic of the MIM element caused by an error in manufacturing or the like. Variations in characteristics can be easily corrected by varying the pulse width w. Further, even when the contrast is adjusted by the contrast adjustment volume, the contrast characteristics with respect to the rotational position of the volume can be made uniform by correcting the drive voltage of the positive selection positive voltage signal.

The present invention is not limited to the above embodiment. For example, an X driver 12 and a Y driver 13
The driving voltage of the signal line side signal and the driving voltage of the scanning line side signal which are respectively output from can be set to the most appropriate voltages in accordance with the characteristics of the liquid crystal panel 11. Also,
Regarding the duty ratio of the positive selection positive voltage signal with respect to the signal width of the scanning line side signal, an example in which the duty ratio is reduced in the present embodiment has been described.However, in the driving method of the liquid crystal display device and the liquid crystal display device according to the present invention, The duty ratio may be increased according to the contrast characteristics of the liquid crystal panel 11. Further, a configuration may be adopted in which a switch or a volume for setting the duty ratio is provided, and the Y driver 13 is controlled so that the duty ratio is set by the switch or the like.

Further, in the present embodiment, the contrast characteristic is corrected by changing the pulse width w of the scanning line side signal output from the Y driver 13. The drive voltage may be changed stepwise. In such a case, the contrast characteristic of the liquid crystal panel 11 can be controlled to an arbitrary characteristic.

In the present embodiment, the two-terminal non-linear resistance element has been described by taking the MIM element as an example. However, the present invention is not limited to this, and the two-terminal element having a conductor-insulator-conductor structure may be used. It suffices if it shows a nonlinear resistance characteristic.

Furthermore, in the present embodiment, an example has been described in which the transmission type liquid crystal panel 11 is driven while correcting the contrast characteristics. However, the driving method of the liquid crystal display device according to the present invention is applied to a reflection type liquid crystal display device. Can also be applied.

Further, the method for driving a liquid crystal display device and the liquid crystal display device according to the present invention can be suitably used for electronic devices and information devices such as mobile phones, electronic organizers, personal computers, and liquid crystal televisions.

[0033]

As described above, according to the driving method of the liquid crystal display device according to the first aspect, the duty ratio of the negative voltage signal for selection in the negative direction and the positive voltage signal for positive selection in the scanning line side signal is varied. In addition, it is possible to uniformly correct the I / V characteristics that fluctuate due to an error in the characteristics of the two-terminal nonlinear resistance element and a manufacturing error, thereby making the contrast characteristics of the liquid crystal display device uniform.

According to a second aspect of the present invention, in the case where the luminance gradation of the liquid crystal display device is controlled by pulse width modulation of the signal on the signal line side,
As a result of making the I / V characteristics of the two-terminal nonlinear resistance element uniform, the set luminance gradation and the actual luminance gradation can always be matched. Further, even when full color is formed using three colors of RGB, the set color always matches the actually displayed color, so that the display color can be made uniform.

According to a third aspect of the present invention, at least one of the minimum value of the negative voltage signal for negative selection and the maximum value of the positive voltage signal for positive selection in the scanning line side signal is corrected. Even when the contrast is adjusted by an adjustment volume or the like, the contrast characteristics with respect to the rotational position of the adjustment volume can be made uniform.

Further, according to the liquid crystal display device of the fourth aspect, the driving means for varying the duty ratio between the negative voltage signal for selection in the negative direction and the positive voltage signal for positive selection in the scanning line side signal is provided. I / V characteristics that fluctuate due to an error in characteristics of the terminal type nonlinear resistance element or a manufacturing error can be uniformly corrected, thereby making the contrast characteristics of the liquid crystal display device uniform. In addition, as a result of making the I / V characteristics of the two-terminal nonlinear resistance element uniform, the set luminance gradation and the actual luminance gradation can always be matched. Furthermore, even when full color is formed by using three colors of RGB, the set color always matches the actually displayed color, so that the display color can be made uniform. In addition, by adjusting at least one of the minimum value of the negative voltage signal of the reverse selection and the maximum value of the positive voltage signal of the positive selection in the scanning line side signal, it is possible to adjust the contrast even when adjusting the contrast with an adjustment volume or the like. The contrast characteristic with respect to the rotational position of the application volume can be made uniform.

[Brief description of the drawings]

FIG. 1 shows Y in a display device according to an embodiment of the present invention.
FIG. 4 is a signal waveform diagram of a scanning line side signal output from a driver.

FIG. 2 shows Y in the display device according to the embodiment of the present invention.
FIG. 9 is another signal waveform diagram of a scanning line side signal output from a driver.

3A is a characteristic diagram of a contrast characteristic CR11, FIG. 3B is a characteristic diagram of a contrast characteristic CR12, FIG. 3C is a characteristic diagram of a contrast characteristic CR13, and FIG. FIG.

FIG. 4 is a characteristic diagram showing I / V characteristics in a Pool-Frenkel plot of a liquid crystal display device to be driven.

FIG. 5 is a contrast characteristic diagram for explaining an example in which contrast characteristics differ due to differences in I / V characteristics.

FIG. 6 is a block diagram of a conventional display device and a display device according to the present embodiment.

FIG. 7A is a signal waveform diagram of a scanning line side signal output from a Y driver in a conventional display device, and FIG.
FIG. 7 is a signal waveform diagram of a signal line side signal output from an X driver in a conventional display device.

[Description of Signs] 1 display device 11 liquid crystal panel 12 X driver 13 Y driver 31 reverse selection negative voltage signal 32 positive selection positive voltage signal

Claims (4)

[Claims] 1. A signal line side signal is output to a signal line side electrode,
And a method of driving a liquid crystal display device that outputs a scanning line side signal comprising a set of a reverse selection negative voltage signal and a positive selection positive voltage signal to a scanning line side electrode, wherein the reverse selection negative voltage signal and the positive selection positive voltage signal are A contrast ratio of the liquid crystal display device is corrected by changing a duty ratio of the liquid crystal display device. 2. The method according to claim 1, wherein the luminance gradation of the liquid crystal display device is controlled by pulse width modulation of the signal on the signal line side. 3. The contrast characteristic of the liquid crystal display device is corrected by correcting at least one of a minimum value of the reverse selection negative voltage signal and a maximum value of the positive selection positive voltage signal. Or a method for driving a liquid crystal display device according to item 2. 4. A driving means for generating and outputting the signal line side signal and the scanning line side signal according to the driving method of the liquid crystal display device according to claim 1. Liquid crystal display device.